A202145 - OEIS

A202145

G.f.: 1 + Sum_{n>=1} x^n * Product_{k=1..n} (1 - x^k) / (1 - x^(2*k+1)).

1, 1, 0, 0, 0, 0, -1, 1, 0, -2, 2, 0, -2, 2, 0, -2, 2, 0, -1, 1, 0, -2, 2, 2, -4, 2, 0, -2, 4, -2, -2, 2, 0, 0, 0, 0, -3, 3, 2, -4, 2, 0, -2, 2, 0, -2, 2, 0, 0, 0, -2, 0, 2, 2, -4, 2, 0, -4, 6, -2, -1, 1, 0, 0, -2, 2, -2, 2, 2, -2, 0, -2, 0, 4, -2, -2, 2, 0

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,10

LINKS

Paul D. Hanna, Table of n, a(n) for n = 0..500

EXAMPLE

G.f.: A(x) = 1 + x - x^6 + x^7 - 2*x^9 + 2*x^10 - 2*x^12 + 2*x^13 - 2*x^15 +... where A(x) = 1 + x*(1-x)/(1-x^3) + x^2*(1-x)*(1-x^2)/((1-x^3)*(1-x^5)) + x^3*(1-x)*(1-x^2)*(1-x^3)/((1-x^3)*(1-x^5)*(1-x^7)) +...

PROG

(PARI) {a(n)=polcoeff(1 + sum(m=1, n, x^m*prod(k=1, m, (1-x^k)/(1-x^(2*k+1) +x*O(x^n)))), n)}

CROSSREFS

Cf. A202146 (partial sums).

Sequence in context: A353768 A140666 A350628 * A130772 A257076 A109265

Adjacent sequences: A202142 A202143 A202144 * A202146 A202147 A202148

KEYWORD

sign

AUTHOR

Paul D. Hanna, Dec 12 2011

STATUS

approved