896324308830domain: NAppears in sequencesa(n) = 1+(n+1)^2+n!+Sum_{k=1..n-1} binomial(n,k)*n!/(n-k)!.at n=13A274294a(n) = (n + 1)^2 + n!*L_n(-1), where L_n(x) is the Laguerre polynomial.at n=13A317094