a(n) = 0! * 1! * 2! * ... * n! - 1.A030428a(n) = 0! * 1! * 2! * ... * n! - 1.Terms a(0) =0a(1) =0a(2) =1a(3) =11a(4) =287a(5) =34559a(6) =24883199a(7) =125411327999External referencesoeis: A030428