OFFSET
0,4
COMMENTS
This definition of triple factorials starts with a(1)=a(2)=1. The main version is A007661.
LINKS
Wikipedia, Multifactorials
MAPLE
A161474 := proc(n) if n < 3 then 1 ; else procname(n-3)*n ; fi; end: seq(A161474(n), n=0..80) ; # R. J. Mathar, Jun 16 2009
MATHEMATICA
multiFactorialRev[n_, k_] := If[n < k, 1, If[n >= k, n*multiFactorialRev[n - k, k]]]; Array[ multiFactorialRev[#, 3] &, 32] (* Robert G. Wilson v, Aug 29 2012 *)
PROG
(Magma) TripleFactorial:=func<n | &*[n..3 by -3]>; [TripleFactorial(n): n in [1..35]]; // Vincenzo Librandi, Apr 08 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Asbel Torres da Cunha (asbeltc(AT)gmail.com), Jun 11 2009
EXTENSIONS
Corrected and extended by R. J. Mathar, Jun 16 2009
a(0)=1 prepended by Alois P. Heinz, May 06 2020
STATUS
approved