OFFSET
0,3
LINKS
Robert Price, Table of n, a(n) for n = 0..803
Eric Weisstein's World of Mathematics, Multifactorial.
FORMULA
a(n)=1 for n < 1, otherwise a(n) = n*a(n-10).
Sum_{n>=0} 1/a(n) = A342033. - Amiram Eldar, May 23 2022
EXAMPLE
a(13) = 13 * 3 * 1 = 39.
MAPLE
a:= n-> `if`(n<1, 1, n*a(n-10)); seq(a(n), n=0..50); # G. C. Greubel, Aug 22 2019
MATHEMATICA
MultiFactorial[n_, k_]:=If[n<1, 1 , n*MultiFactorial[n-k, k]];
Table[MultiFactorial[i, 10], {i, 0, 100}]
Table[Times@@Range[n, 1, -10], {n, 0, 50}] (* Harvey P. Dale, Aug 11 2019 *)
PROG
(PARI) a(n)=if(n<1, 1, n*a(n-10));
vector(40, n, n--; a(n) ) \\ G. C. Greubel, Aug 22 2019
(Magma) b:=func< n | n le 10 select n else n*Self(n-10) >;
[1] cat [b(n): n in [1..50]]; // G. C. Greubel, Aug 22 2019
(Sage)
def a(n):
if (n<1): return 1
else: return n*a(n-10)
[a(n) for n in (0..50)] # G. C. Greubel, Aug 22 2019
(GAP)
a:= function(n)
if n<1 then return 1;
else return n*a(n-10);
fi;
end;
List([0..50], n-> a(n) ); # G. C. Greubel, Aug 22 2019
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Robert Price, Jun 07 2017
STATUS
approved