A173324 a(n) = 3*n! + 1.

4, 4, 7, 19, 73, 361, 2161, 15121, 120961, 1088641, 10886401, 119750401, 1437004801, 18681062401, 261534873601, 3923023104001, 62768369664001, 1067062284288001, 19207121117184001, 364935301226496001, 7298706024529920001, 153272826515128320001

Offset: 0

Author

Vincenzo Librandi, Feb 16 2010

Keywords

• nonn
• easy

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..200

Crossrefs

Cf. sequences of the type k*n!+1: A038507 (k=1), A052898 (k=2), this sequence, A173322 (k=4), A173319 (k=5), A173314 (k=6).

Programs

Magma

[3*Factorial(n) + 1: n in [0..25]]; // Vincenzo Librandi, Sep 29 2013

Magma

[4] cat [n eq 1 select n+3 else n*Self(n-1)-n+1: n in [1..25] ]; // Vincenzo Librandi, Sep 29 2013

Maple

a:= proc(n) if n=0 then 4 else a(n):= n*a(n-1)-n+1 fi end: seq (a(n), n=0..25);  # Sergei N. Gladkovskii, Jul 04 2012

Mathematica

Table[3 n! + 1, {n, 0, 30}] (* Vincenzo Librandi, Sep 29 2013 *)

Formula

a(0) = 4, a(n) = n*a(n-1)-n+1 for n>0. - Sergei N. Gladkovskii, Jul 04 2012