-851968domain: ZAppears in sequencesa(0)=1. a(n) = 2^(n-2)*(5-n), for n>0.at n=18A172160a(n)= +2*a(n-2) +4*a(n-3), n>3.at n=18A173559a(n) = Sum_{k=0..n} k^3 * (-1)^k * 3^(n-k) * binomial(n,k).at n=13A383150