A069152 a(n) = (n-1)!-n^tau(n)/n^2.

0, 1, 2, 23, 84, 719, 4976, 40311, 362780, 3628799, 39896064, 479001599, 6227020604, 87178290975, 1307674363904, 20922789887999, 355687427991024, 6402373705727999, 121645100408672000, 2432902008176639559

Offset: 2

Author

Benoit Cloitre, Apr 08 2002

Keywords

• easy
• nonn

Comments

n and a(n) have the same parity.

Crossrefs

Cf. A062758.

Programs

Mathematica

Table[(n - 1)! - n^DivisorSigma[0, n]/n^2, {n, 2, 25}] (* Wesley Ivan Hurt, Jan 20 2024 *)