OFFSET
0,3
COMMENTS
Zeroless analog of factorial numbers.
A very crude calculation suggests a(n) may grow like n^10. I don't really believe that, but certainly a(n) grows very slowly in comparison with n!. - N. J. A. Sloane, Sep 03 2014
LINKS
N. J. A. Sloane, Table of n, a(n) for n = 0..10000
MAPLE
noz:=proc(n) local a, t1, i, j; a:=0; t1:=convert(n, base, 10); for i from 1 to nops(t1) do j:=t1[nops(t1)+1-i]; if j <> 0 then a := 10*a+j; fi; od: a; end;
t1:=[1]; for n from 1 to 50 do t1:=[op(t1), noz(n*t1[n])]; od: t1;
MATHEMATICA
nxt[{n_, a_}]:={n+1, FromDigits[DeleteCases[IntegerDigits[a(n+1)], 0]]}; NestList[nxt, {0, 1}, 40][[;; , 2]] (* Harvey P. Dale, Feb 13 2024 *)
PROG
(Python)
from itertools import count, islice
def noz(n): return int(str(n).replace("0", ""))
def agen(): # generator of terms
yield (an:=1)
yield from (an:=noz(n*an) for n in count(1))
print(list(islice(agen(), 32))) # Michael S. Branicky, Jul 02 2024
CROSSREFS
KEYWORD
nonn,base
AUTHOR
N. J. A. Sloane, Jun 11 2014
STATUS
approved