47679domain: NAppears in sequencesG.f.: A(x) = 1 + x*A(x)*A(-x) + x^2*exp( Sum_{n>=1} 2*L(n)^2*x^(2*n)/n ), where A(x) = exp(Sum_{n>=1} L(n)*x^n/n).at n=29A205566Compound filter: a(n) = P(sigma(n), sigma(2n)), where P(n,k) is sequence A000027 used as a pairing function, and sigma is the sum of divisors (A000203).at n=49A286359