OFFSET
0,3
COMMENTS
Invert transform of A001227.
LINKS
Robert Israel, Table of n, a(n) for n = 0..2986
N. J. A. Sloane, Transforms
FORMULA
G.f.: 1/(1 - Sum_{k>=1} x^(k*(k+1)/2)/(1 - x^k)).
G.f.: 1/(1 + x * (d/dx) log(Product_{k>=1} (1 - x^(2*k-1))^(1/(2*k-1)))).
a(0) = 1; a(n) = Sum_{k=1..n} A001227(k)*a(n-k).
MAPLE
a:=series(1/(1-add(x^k/(1-x^(2*k)), k=1..100)), x=0, 33): seq(coeff(a, x, n), n=0..32); # Paolo P. Lava, Apr 02 2019
MATHEMATICA
nmax = 32; CoefficientList[Series[1/(1 - Sum[x^k/(1 - x^(2 k)), {k, 1, nmax}]), {x, 0, nmax}], x]
nmax = 32; CoefficientList[Series[1/(1 - Sum[x^(k (k + 1)/2)/(1 - x^k), {k, 1, nmax}]), {x, 0, nmax}], x]
a[0] = 1; a[n_] := a[n] = Sum[Sum[Mod[d, 2], {d, Divisors[k]}] a[n - k], {k, 1, n}]; Table[a[n], {n, 0, 32}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Oct 18 2018
STATUS
approved