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A243657 Zeroless factorials: a(0)=1; thereafter a(n) = noz(n*a(n-1)), where noz(n) = A004719(n) omits the zeros from n. 5
1, 1, 2, 6, 24, 12, 72, 54, 432, 3888, 3888, 42768, 513216, 667188, 934632, 141948, 2271168, 3869856, 6965748, 132349212, 264698424, 555866694, 1222967268, 28128247164, 67577931936, 16894482984, 439256557584, 1185992754768, 332779713354, 965611687266, 289683561798, 89819415738 (list; graph; refs; listen; history; text; internal format)
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;

CROSSREFS

Cf. A000142, A004719, A242350, A243063, A243658.

Sequence in context: A334795 A181952 A256270 * A321475 A004154 A076126

Adjacent sequences:  A243654 A243655 A243656 * A243658 A243659 A243660

KEYWORD

nonn,base

AUTHOR

N. J. A. Sloane, Jun 11 2014

STATUS

approved

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Last modified August 10 19:52 EDT 2020. Contains 336381 sequences. (Running on oeis4.)