A295473 a(0) = 0; for n>0, a(n) = 9*n!.

0, 9, 18, 54, 216, 1080, 6480, 45360, 362880, 3265920, 32659200, 359251200, 4311014400, 56043187200, 784604620800, 11769069312000, 188305108992000, 3201186852864000, 57621363351552000, 1094805903679488000, 21896118073589760000, 459818479545384960000

Offset: 0

Author

Vincenzo Librandi, Feb 14 2018

Keywords

• nonn
• easy

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..300

Crossrefs

Cf. A000142.

Cf. similar sequences listed in A298881.

Programs

Magma

[n eq 0 select 0 else 9*Factorial(n): n in [0..25]];

Mathematica

Join[{0}, 9 Range[25]!]

PARI

a(n) = (n > 0)*9*n! \\ Felix Fröhlich, Feb 15 2018

Formula

E.g.f.: 9*x/(1-x).

a(n) = n*a(n-1) = 9*A000142(n) for n>0.