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A341794
Number of ways to write n as an ordered sum of 3 nonzero tetrahedral numbers.
8
1, 0, 0, 3, 0, 0, 3, 0, 0, 4, 0, 0, 6, 0, 0, 3, 0, 0, 3, 3, 0, 3, 6, 0, 0, 3, 0, 1, 6, 0, 0, 6, 0, 0, 3, 0, 0, 9, 3, 0, 3, 3, 0, 6, 0, 0, 6, 3, 0, 0, 0, 0, 3, 6, 0, 3, 6, 1, 6, 0, 0, 3, 6, 0, 6, 0, 0, 6, 3, 0, 0, 3, 3, 3, 6, 0, 0, 9, 0, 0, 0, 0, 0, 9, 0, 0, 6, 3, 0, 9, 0, 0, 12
OFFSET
3,4
FORMULA
G.f.: ( Sum_{k>=1} x^binomial(k+2,3) )^3.
MATHEMATICA
nmax = 95; CoefficientList[Series[Sum[x^Binomial[k + 2, 3], {k, 1, nmax}]^3, {x, 0, nmax}], x] // Drop[#, 3] &
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Feb 19 2021
STATUS
approved