66076419domain: NAppears in sequencesa(n) = floor((-1 + 2^n)/(1 + 2*n)).at n=31A191630a(n) = floor((1 + 2^n)/(1 + 2*n)).at n=31A191633a(n) = floor((1 + 4^n)/(1 + 4*n)).at n=15A191641