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A111335 Let qf(a,q) = Product(1-a*q^j,j=0..infinity); g.f. is qf(q^3,q^4)/qf(q,q^4). 3
1, 1, 1, 0, 0, 1, 1, 0, -1, 0, 2, 1, -1, -1, 1, 2, -1, -2, 1, 3, 1, -3, -1, 3, 1, -3, -2, 4, 4, -3, -4, 3, 5, -3, -7, 2, 9, 0, -9, -1, 10, 3, -11, -5, 12, 8, -11, -10, 10, 12, -11, -15, 11, 19, -7, -21, 6, 24, -5, -28, 1, 31, 4, -33, -8, 36, 12, -38, -18, 40, 27, -40, -33, 40, 39, -40, -49, 38, 60, -34, -67, 30, 75, -25, -87, 18, 98 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,11

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..1000

FORMULA

Euler transform of period 4 sequence [1, 0, -1, 0, ...]. - Michael Somos, Nov 10 2005

G.f.: Product_{k>0} (1-x^(2k-1))^((-1)^k). - Michael Somos, Nov 11 2005

PROG

(PARI) {a(n)=if(n<0, 0, polcoeff( prod(k=0, n\2, (1-x^(2*k+1))^(-(-1)^k), 1+x*O(x^n)), n))} /* Michael Somos, Nov 11 2005 */

CROSSREFS

Cf. A111330.

Sequence in context: A337006 A025892 A025883 * A345238 A242442 A163768

Adjacent sequences:  A111332 A111333 A111334 * A111336 A111337 A111338

KEYWORD

sign

AUTHOR

N. J. A. Sloane, Nov 09 2005

STATUS

approved

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Last modified January 23 17:33 EST 2022. Contains 350514 sequences. (Running on oeis4.)