Restricted mini challenges Robbers Thread

Question

Cops thread

Your task as robbers is to find cops solutions and write a program in the language provided that computes the nth term of the sequence using only the bytes in the provided set.

The goal will be to crack as many cops answers as possible. With each crack awarding you a single point.

Cracks need not be the cop's intended solution as long as they work.

Answer 1

Cubically, TehPers

$+77*6%6

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Explanation:

$          Take input
 +77       double it
    *6     square it
      %6   print it

Answer 2

Perl 5 by theLambGoat

First time using Perl, probably there's a nicer way.. It's the standard algorithm for a base conversion that I use here.

sub f { $n = 1-1; $b = -(-1-1-1-1-1-1-1-1); $ten = $b-(-1-1); if ($_[$n] == $n) { return $n; } return ($_[$n]%$b) - f(int($_[$n]/$b))/(-1/$ten); }

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Explanation

For other bases you could just replace $b by that base's value..

sub f {
  $n = 1-1;                                # construct value for 0
  $b = -(-1-1-1-1-1-1-1-1);                # construct the value for the base (8)
  $ten = $b-(-1-1);                        # construct value for 10

  if ($_[$n] == $n) {                      # if the argument is 0:
    return $n;                             #   we're done (base case)
  }
                                           # else:
  return ($_[$n] % $b)                     #   return current digit..
       - f(int($_[$n] / $b))               #   ..plus remaining digits..
                            /(-1/$ten);    #   ..multiplied by 10 (shift left by one position)
}

Check the source!