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A306704 Expansion of Sum_{k>=0} x^(k*(k+1)/2) / Product_{j=1..k} (1 + j*x^j). 1
1, 1, -1, 2, -2, 0, 1, 3, -5, -6, 11, 11, -12, -35, 33, 35, -22, -102, 170, 47, -224, -491, 874, 695, -598, -2606, 2246, 1503, -664, -6420, 11590, 2526, -13762, -34647, 61785, 37119, -32372, -181052, 147105, 104896, 12824, -436333, 799007, -109587, -868230, -2316921, 4447531 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Table of n, a(n) for n=0..46.

MATHEMATICA

nmax = 46; CoefficientList[Series[Sum[x^(k (k + 1)/2)/Product[(1 + j x^j), {j, 1, k}], {k, 0, nmax}], {x, 0, nmax}], x]

CROSSREFS

Cf. A003406, A204856.

Sequence in context: A277938 A130020 A292870 * A091063 A246935 A342120

Adjacent sequences:  A306701 A306702 A306703 * A306705 A306706 A306707

KEYWORD

sign

AUTHOR

Ilya Gutkovskiy, Mar 05 2019

STATUS

approved

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Last modified June 13 14:17 EDT 2021. Contains 345001 sequences. (Running on oeis4.)