

A300575


Coefficient of x^n in (1+x)(1x^3)(1+x^5)(1x^7)(1+x^9)...


3



1, 1, 0, 1, 1, 1, 1, 1, 2, 0, 2, 0, 3, 1, 3, 2, 3, 3, 3, 4, 3, 6, 2, 7, 1, 8, 0, 10, 2, 11, 4, 12, 7, 13, 10, 13, 13, 13, 17, 13, 22, 11, 26, 9, 31, 6, 36, 2, 41, 3, 46, 9, 51, 17, 55, 26, 59, 36, 62, 48, 63, 61, 64, 75, 64, 92, 60, 109, 55, 127, 48, 147, 37, 167
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OFFSET

0,9


LINKS

Seiichi Manyama, Table of n, a(n) for n = 0..1000


FORMULA

O.g.f.: Product_{n >= 0} (1 + (1)^n x^(2n+1)).
a(n) = Sum (1)^k where the sum is over all strict integer partitions of n into odd parts and k is the number of parts not congruent to 1 modulo 4.


MATHEMATICA

CoefficientList[Series[QPochhammer[x, x^2], {x, 0, 100}], x]


CROSSREFS

Cf. A000009, A010815, A027193, A067659, A078408, A081362, A220418, A290261, A292043, A292137, A300574.
Sequence in context: A042961 A029190 A166865 * A029189 A035432 A029224
Adjacent sequences: A300572 A300573 A300574 * A300576 A300577 A300578


KEYWORD

sign,look


AUTHOR

Gus Wiseman, Mar 09 2018


STATUS

approved



