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 A281084 Expansion of Product_{k>=0} (1 + x^(3*k*(k+1)+1)). 5
 1, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 0, 0, 0, 2, 2, 0, 0, 0, 0, 0, 1 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,99 COMMENTS Number of partitions of n into distinct centered hexagonal numbers (A003215). LINKS G. C. Greubel, Table of n, a(n) for n = 0..1000 Eric Weisstein's World of Mathematics, Hex Number FORMULA G.f.: Product_{k>=0} (1 + x^(3*k*(k+1)+1)). EXAMPLE a(98) = 2 because we have [91, 7] and [61, 37]. MATHEMATICA nmax = 105; CoefficientList[Series[Product[1 + x^(3 k (k + 1) + 1), {k, 0, nmax}], {x, 0, nmax}], x] CROSSREFS Cf. A003215, A279279, A280953, A281081, A281082, A281083. Sequence in context: A300717 A191928 A033148 * A186230 A214304 A248640 Adjacent sequences:  A281081 A281082 A281083 * A281085 A281086 A281087 KEYWORD nonn AUTHOR Ilya Gutkovskiy, Jan 14 2017 STATUS approved

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Last modified July 7 12:47 EDT 2022. Contains 355148 sequences. (Running on oeis4.)