775054domain: NAppears in sequencesa(n) = a(1) + a(2) + ... + a(n-1) + a(m) for n >= 4, where m = 2*n - 3 - 2^(p+1) and p is the unique integer such that 2^p < n - 1 <= 2^(p+1), starting with a(1) = a(2) = a(3) = 1.at n=20A049932G.f. A(x) satisfies: A(x) = x * Product_{k>=1} (1 + A(x^k))^k.at n=16A308370