Calculate power series result [duplicate]

Question

^{Related: Calculate Power Series Coefficients}

Given a positive integer \$X\$ and a max exponent (Also a positive integer too) \$N\$ calculate the result of a power series. Example:

$$X^0+X^1+X^2+\cdots +X^N$$

• Assume \$(X + N) \le 100\$

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Test Cases

1 2  => 3
2 3  => 15
3 4  => 121
2 19 => 1048575

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Standard code-golf rules apply.

Answer 1

Pyth, 14 13 bytes

AQVhH=+Z^GN)Z

Try it online!

How it works

assign('Q',eval_input())
assign('[G,H]',Q)
for N in num_to_range(head(H)):
 assign('Z',plus(Z,Ppow(G,N)))
imp_print(Z)

Answer 2

Batch, 61 bytes

@set s=0
@for /l %%i in (0,1,%2)do @set/as=s*%1+1
@echo %s%

Using @tsh's algorithm.

Answer 3

Charcoal, 9 7 bytes

Ｉ↨ＮＥ⊕Ｎ¹

Try it online! Link is to verbose version of code. Uses @Bubbler's algorithm. Explanation:

     Ｎ  Second input as a number
    ⊕   Increment
   Ｅ  ¹ Make list of `1`s of that length
  Ｎ     First input as a number
 ↨      Base conversion
Ｉ       Cast to string
        Implicitly print

Answer 4

Swift 4.0, 100 bytes

func a(x:Int,n:Int)->Int{return(0...n).reduce(0,{p,q in p+(q>=1 ?(1...q).reduce(1,{a,_ in a*x}):1)})}

Try it online!

Ungolfed

func a(x:Int, n:Int) -> Int {
  return (0...n).reduce(0,        // For 0 to n
    { p, q in                     // p is result of last cycle, q the current element
      p +                         // Add p to
      ( q > 0 ?                   // If current element is not 0 
        (1...q).reduce(1, { a, _ in a*x } ) // pow(x, n) *
        : 1                       // Otherwise, 1
      ) 
    } 
  )
}

* The reduce is shorter than:
import Foundation
[...] Int(pow(Double(x),Double(q)))

First golf I do, so could be much more golfable, but finally the super-verbose Swift has a chance to be used!