OFFSET
0,2
COMMENTS
Euler transform of 2 * A000048(n).
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..1000
OEIS Wiki, Euler transform
FORMULA
G.f.: A(x) = 1 / ( Product_{k>=1} (1 - x^k)^A000048(k) )^2.
EXAMPLE
A(x)^2 = 1 + 4*x + 14*x^2 + 40*x^3 + 109*x^4 + 276*x^5 + 678*x^6 + ... .
PROG
(PARI) b(n, k) = sumdiv(n, d, (gcd(d, k)==1)*(moebius(d)*k^(n/d)))/(k*n);
my(N=40, x='x+O('x^N)); Vec(1/prod(k=1, N, (1 - x^k)^b(k, 2))^2)
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jul 04 2024
STATUS
approved