3019941domain: NAppears in sequencesa(n) = a(n-1) + 2*a(n-2) - a(n-3), where a(0) = 2, a(1) = 4, a(2) = 7.at n=24A287381p-INVERT of (1,1,1,1,1,...), where p(S) = (1 - S^3)^2.at n=12A291015