OFFSET
0
LINKS
Eric Weisstein's World of Mathematics, Biquadratic Number
FORMULA
G.f.: Product_{k>=1} (1 + x^(k^4)).
MATHEMATICA
nmax = 98; CoefficientList[Series[Product[1 + x^k^4, {k, 1, Floor[nmax^(1/4) + 1]}], {x, 0, nmax}], x]
CROSSREFS
KEYWORD
nonn
AUTHOR
_Ilya Gutkovskiy_, Jan 27 2018
STATUS
approved