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
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Jan 14 2017
STATUS
approved