OFFSET
0,4
LINKS
FORMULA
a(n) = 1 if n in A112886.
EXAMPLE
a(6) = 4 because 6 has 4 divisors {1, 2, 3, 6} among which 3 are triangular numbers {1, 3, 6} therefore we have [6], [3, 3], [3, 1, 1, 1] and [1, 1, 1, 1, 1, 1].
MATHEMATICA
Table[SeriesCoefficient[Product[1/(1 - Boole[Mod[n, k] == 0 && IntegerQ[Sqrt[8 k + 1]]] x^k), {k, 1, n}], {x, 0, n}], {n, 0, 95}]
CROSSREFS
KEYWORD
nonn,look
AUTHOR
Ilya Gutkovskiy, Oct 28 2017
STATUS
approved