# Find the hardest OEIS sequence to golf!

Notice: This question originally had people write comments with a shorter program, rather than new answers. This has been changed so that people with shorter programs can get reputation too. Hopefully this doesn't become unmanageable...

There have been a couple of OEIS-related questions recently, so here's another:

Pick a sequence from the Online Encyclopedia of Integer Sequences, and write a full program or function which computes the sequence in one of the following ways:

• It prints every term in the sequence in order
• It takes an index in the sequence as input, and returns/outputs the term at that index.

You will be trying to pick the sequence with the longest possible shortest possible program/function to compute that sequence (see the example below if that's confusing). You must include which sequence you are using in your answer.

Try to make your program/function as short as possible. If anyone can find a shorter program which computes the same sequence, they should add a another answer with their shorter program. If you do find a shorter program than someone else, you should refer to their answer in yours. For all answers, a Try it Online link would be nice. If someone else has written a shorter program than yours, it would be nice if you put a link to it in your answer.

Of course, none of the programs should access the internet or the OEIS in any way, and they should all theoretically work on arbitrarily large inputs (you can ignore things like the maximum size of an integer type).

The sequence with the longest shortest program in bytes is the winner.

## For example,

Let's say I pick the sequence A000027, the positive integers, and I submit this answer:

# Python, 49 bytes, A000027

x = "o"
while True:
print len(x)
x += "o"


Obviously this is not a very short program for computing that sequence, so someone else (let's call them foo) might come along and add this answer:

# Haskell, 2 bytes, A000027:

id


(id is the identity function, so it will just return whatever you pass into it, and because the nth positive integer is just n, it will compute that sequence).

Then, the person who posted the Python solution should edit their answer:

# Python, 49 bytes, A000027

Superseded by foo's answer (link).

x = "o"
while True:
print len(x)
x += "o"


As long as no one else finds a shorter program, this sequence would get a score of 2 (because id is two bytes), and the sequence with the highest score wins.

Current best sequence: A014715, 252 bytes

• Isn't this trivially just something like A060843? – Expired Data Jul 11 '19 at 11:59
• The answer with the longest sequence is the winner. don't you mean that the answer with the longest answer in bytes is the winner? – Expired Data Jul 11 '19 at 12:04
• Should one update their answer with the current shortest program? – TFeld Jul 11 '19 at 12:50
• Honestly, the more I think about this question, the more it becomes obvious that the optimal strategy is finding challenges that are based on OEIS sequences and copying the shortest answer. – Stephen Jul 11 '19 at 12:54
• This looks like a cops-and-robbers done wrong because there's no incentive for the robbers. It might be worth taking it to the sandbox and enlisting mod help to lock it until it can be reworked. – Peter Taylor Jul 11 '19 at 21:31

# Wolfram Language (Mathematica), 270 252 bytes A014715

252 bytes, by Expired Data

RealDigits[NSolve[3x-6==Plus@@({6,-12,4,-7,7,-1,0,-5,2,4,12,-2,-7,-12,7,10,4,-3,-9,7,0,8,-14,3,-9,-2,3,10,2,6,-1,-10,3,-1,-7,7,-7,12,5,-8,-6,-10,8,8,7,3,-9,-1,-6,-6,2,3,10,2,-3,-5,-2,1,1,1,1,1,-1,-2,-2,1,2,1,0,-1}x^2~Range~71),x,#][[-1,-1,-1]]][[1,#]]&


Try it online!

I've never golfed in mathematica before, but the sequence seemed like an obvious contender. The code is more or less a copy of the example on the OEIS page.

The sequence is the decimal expansion of Conway's constant, which itself is the root of this polynomial:

$$\x^{71}-x^{69}-2x^{68}-x^{67}+2x^{66}+2x^{65}+x^{64}-x^{63}-x^{62}-x^{61}-x^{60}-x^{59}+2x^{58}+5x^{57}+3x^{56}-2x^{55}-10x^{54}-3x^{53}-2x^{52}+6x^{51}+6x^{50}+x^{49}+9x^{48}-3x^{47}-7x^{46}-8x^{45}-8x^{44}+10x^{43}+6x^{42}+8x^{41}-5x^{40}-12x^{39}+7x^{38}-7x^{37}+7x^{36}+x^{35}-3x^{34}+10x^{33}+x^{32}-6x^{31}-2x^{30}-10x^{29}-3x^{28}+2x^{27}+9x^{26}-3x^{25}+14x^{24}-8x^{23}-7x^{21}+9x^{20}+3x^{19}-4x^{18}-10x^{17}-7x^{16}+12x^{15}+7x^{14}+2x^{13}-12x^{12}-4x^{11}-2x^{10}+5x^{9}+x^{7}-7x^{6}+7x^{5}-4x^{4}+12x^{3}-6x^{2}+3x-6\$$

• Probably important to mention that the code is copied straight from the OEIS page for the sequence – Stephen Jul 11 '19 at 14:34
• 261 bytes – Expired Data Jul 11 '19 at 15:37
• And a few bytes more by jiggling the equation around – Expired Data Jul 11 '19 at 15:44
• @Stephen Well, I did reverse the polynomial to save a few bytes :P – TFeld Jul 11 '19 at 16:03
• @ExpiredData I've edited it into the answer. – TFeld Jul 11 '19 at 16:05

# Python 3, 3 bytes, A055642

Finally, a ridiculously short answer that isn't just A000027 or some other stupidly simple sequence.

len


This is a function. Number should be inputted as a string of its digits. Undefined behavior for non-integers and other strings.

# cQuents, 1 byte, A000027

\$


Try it online!

Just to have a baseline answer in case every other answer is cracked.

• Jelly, 0 bytes: Try it online! (sorry). Arguments are added to the stack in Jelly, and the top thing on the stack is printed when the program finishes, so the program takes an index as input, and outputs the corresponding term (which is just the same number). – pommicket Jul 11 '19 at 12:32
• @LeoTenenbaum ah, I remembered having the shortest answer to this and forgot that you had two different input styles – Stephen Jul 11 '19 at 12:52
• The 0 bytes version also works in GolfScript. Try it online! – jimmy23013 Jul 11 '19 at 13:12