OFFSET
0,6
LINKS
Eric Weisstein's World of Mathematics, Biquadratic Number
FORMULA
a(n) = [x^(n^4)] (Sum_{k>=1} x^(k^4))^n.
EXAMPLE
a(6) = 6 because we have [256, 256, 256, 256, 256, 16], [256, 256, 256, 256, 16, 256], [256, 256, 256, 16, 256, 256], [256, 256, 16, 256, 256, 256], [256, 16, 256, 256, 256, 256] and [16, 256, 256, 256, 256, 256].
MATHEMATICA
a[0] = 1; a[n_] := Coefficient[Sum[x^k^4, {k, n-1}]^n // Expand, x, n^4]; Table[an = a[n]; Print["a(", n, ") = ", an]; an, {n, 0, 25}] (* Jean-François Alcover, Feb 05 2018 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Feb 04 2018
EXTENSIONS
More terms from Alois P. Heinz, Feb 04 2018
STATUS
approved