|
%I #14 Sep 08 2022 08:46:20
%S 0,9,18,54,216,1080,6480,45360,362880,3265920,32659200,359251200,
%T 4311014400,56043187200,784604620800,11769069312000,188305108992000,
%U 3201186852864000,57621363351552000,1094805903679488000,21896118073589760000,459818479545384960000
%N a(0) = 0; for n>0, a(n) = 9*n!.
%H Vincenzo Librandi, <a href="/A295473/b295473.txt">Table of n, a(n) for n = 0..300</a>
%F E.g.f.: 9*x/(1-x).
%F a(n) = n*a(n-1) = 9*A000142(n) for n>0.
%t Join[{0}, 9 Range[25]!]
%o (Magma) [n eq 0 select 0 else 9*Factorial(n): n in [0..25]];
%o (PARI) a(n) = (n > 0)*9*n! \\ _Felix Fröhlich_, Feb 15 2018
%Y Cf. A000142.
%Y Cf. similar sequences listed in A298881.
%K nonn,easy
%O 0,2
%A _Vincenzo Librandi_, Feb 14 2018
|
