a(n) = Sum_{k=0..n} k!*(k+1)!.A016065a(n) = Sum_{k=0..n} k!*(k+1)!.Terms a(0) =1a(1) =3a(2) =15a(3) =159a(4) =3039a(5) =89439a(6) =3718239a(7) =206931039a(8) =14838252639External referencesoeis: A016065