login
A303172
Number of ordered ways of writing n as a sum of n square pyramidal numbers.
2
1, 1, 1, 1, 1, 6, 31, 106, 281, 631, 1306, 2806, 6931, 19306, 55070, 150816, 391161, 977501, 2426071, 6141865, 16000186, 42465571, 112950916, 297793651, 776866355, 2015237231, 5233754306, 13668689206, 35908153534, 94633042267, 249398115466, 656105299636, 1723150461561
OFFSET
0,6
FORMULA
a(n) = [x^n] (Sum_{k>=0} x^(k*(k+1)*(2*k+1)/6))^n.
a(n) = A290430(n,n).
MATHEMATICA
Table[SeriesCoefficient[Sum[x^(k (k + 1) (2 k + 1)/6), {k, 0, n}]^n, {x, 0, n}], {n, 0, 32}]
CROSSREFS
Main diagonal of A290430.
Sequence in context: A112562 A244716 A024447 * A354552 A143568 A351935
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Apr 19 2018
STATUS
approved