A281084 Expansion of Product_{k>=0} (1 + x^(3*k*(k+1)+1)).

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

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

Index entries for sequences related to centered polygonal numbers

Index entries for related partition-counting sequences

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: A191928 A359887 A033148 * A186230 A214304 A248640

Adjacent sequences: A281081 A281082 A281083 * A281085 A281086 A281087

Keyword

nonn

Author

Ilya Gutkovskiy, Jan 14 2017

Status

approved