OFFSET
0,3
FORMULA
G.f.: x * Product_{k>=0} (1 + 8*x^(2^k) + x^(2^(k+1))).
MATHEMATICA
a[0] = 0; a[1] = 1; a[n_] := If[EvenQ[n], 8 a[n/2], a[(n - 1)/2] + a[(n + 1)/2]]; Table[a[n], {n, 0, 52}]
nmax = 52; CoefficientList[Series[x Product[(1 + 8 x^(2^k) + x^(2^(k + 1))), {k, 0, Floor[Log[2, nmax]] + 1}], {x, 0, nmax}], x]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Mar 16 2021
STATUS
approved