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A307569 Expansion of Product_{j>=1} (1 + x^j*Product_{k>=1} (1 + x^k)^j). 1
1, 1, 2, 5, 13, 31, 77, 188, 458, 1113, 2693, 6494, 15614, 37441, 89563, 213771, 509166, 1210327, 2871563, 6800559, 16077631, 37948242, 89432015, 210456759, 494577391, 1160743593, 2720787358, 6369890095, 14895975508, 34795635421, 81192795264, 189262428612, 440739646423, 1025383979625 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..33.

FORMULA

G.f.: g(x*g(x)), where g(x) = g.f. of A000009.

MATHEMATICA

nmax = 33; CoefficientList[Series[Product[(1 + x^j Product[(1 + x^k)^j, {k, 1, nmax}]), {j, 1, nmax}], {x, 0, nmax}], x]

CROSSREFS

Cf. A000009, A238440, A307128.

Sequence in context: A068739 A063636 A076501 * A200772 A099515 A056367

Adjacent sequences:  A307566 A307567 A307568 * A307570 A307571 A307572

KEYWORD

nonn

AUTHOR

Ilya Gutkovskiy, Apr 15 2019

STATUS

approved

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Last modified July 20 16:15 EDT 2019. Contains 325185 sequences. (Running on oeis4.)