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A306730
Expansion of Sum_{k>=0} x^k * Product_{j=1..k} (1 + j*x^j).
0
1, 1, 2, 2, 4, 6, 9, 12, 22, 32, 45, 70, 98, 153, 231, 318, 452, 685, 933, 1387, 1988, 2769, 3850, 5433, 7622, 10530, 14896, 20635, 28123, 38934, 53067, 72144, 99509, 133661, 183794, 249130, 333956, 448306, 605165, 807053, 1078093, 1444021, 1913418, 2556415, 3406636
OFFSET
0,3
MATHEMATICA
nmax = 44; CoefficientList[Series[Sum[x^k Product[(1 + j x^j), {j, 1, k}], {k, 0, nmax}], {x, 0, nmax}], x]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Mar 06 2019
STATUS
approved