360040domain: NAppears in sequencesa(n) = a(1) + a(2) + ... + a(n-1) + a(m) for n >= 4, where m = 2^(p+1) + 2 - n and p is the unique integer such that 2^p < n-1 <= 2^(p+1), starting with a(1) = a(2) = 1 and a(3) = 4.at n=18A049945a(n) = 900*n^2 + 2*n.at n=19A158406a(n) = 1600*n^2 + 40.at n=14A158775