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A217670 G.f.: Sum_{n>=0} x^n/(1 + x^n)^n. 2
1, 1, 0, 2, -2, 2, 0, 2, -8, 8, 0, 2, -12, 2, 0, 32, -36, 2, 0, 2, -20, 58, 0, 2, -136, 72, 0, 92, -28, 2, 0, 2, -272, 134, 0, 422, -288, 2, 0, 184, -480, 2, 0, 2, -44, 1232, 0, 2, -2360, 926, 0, 308, -52, 2, 0, 2004, -1176, 382, 0, 2, -4064, 2, 0, 6470, -5128, 3642 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Paul D. Hanna, Table of n, a(n) for n = 0..1000

FORMULA

a(4*n+2) = 0 for n>=0.

EXAMPLE

G.f.: A(x) = 1 + x + 2*x^3 - 2*x^4 + 2*x^5 + 2*x^7 - 8*x^8 + 8*x^9 +...

where

A(x) = 1 + x/(1+x) + x^2/(1+x^2)^2 + x^3/(1+x^3)^3 + x^4/(1+x^4)^4 + x^5/(1+x^5)^5 +...

MATHEMATICA

terms = 100; Sum[x^n/(1 + x^n)^n, {n, 0, terms}] + O[x]^terms // CoefficientList[#, x]& (* Jean-Fran├žois Alcover, May 16 2017 *)

PROG

(PARI) {a(n)=polcoeff(sum(m=0, n, x^m/(1+x^m +x*O(x^n))^m), n)}

for(n=0, 100, print1(a(n), ", "))

CROSSREFS

Cf. A217668.

Sequence in context: A215594 A230291 A059288 * A243310 A197727 A176884

Adjacent sequences:  A217667 A217668 A217669 * A217671 A217672 A217673

KEYWORD

sign

AUTHOR

Paul D. Hanna, Oct 10 2012

STATUS

approved

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Last modified February 25 16:14 EST 2018. Contains 299653 sequences. (Running on oeis4.)