12252937700domain: NAppears in sequencesa(0) = 0. If n is odd, a(n) = a(n-1) + n, otherwise a(n) = a(n-1) * n.at n=20A077138a(n) = (a(n-1)+(2n-1))*(2n) with a(0) = 0.at n=10A093302