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A045550 Numbers whose factorial has '8' as its final nonzero digit. 6
9, 10, 11, 13, 15, 16, 18, 22, 27, 30, 31, 33, 39, 44, 54, 57, 70, 71, 73, 77, 80, 81, 83, 89, 94, 102, 105, 106, 108, 114, 119, 125, 126, 128, 137, 142, 149, 154, 157, 170, 171, 173, 184, 185, 186, 188, 190, 191, 193, 197, 204, 207, 220, 221, 223 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

From Robert Israel, Dec 16 2016: (Start)

If n is in the sequence, then:

if n == 0 (mod 5), n+1 is in the sequence;

if n == 1 (mod 5), n+1 is in A045549;

if n == 2 (mod 5), n+1 is in A045548;

if n == 3 (mod 5), n+1 is in A045547. (End)

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000 (n=1..1000 from Harvey P. Dale)

Index entries for sequences related to final digits of numbers

MAPLE

count:= 0:

r:= 1:

for n from 2 while count < 100 do

  r:= r*n;

  if r mod 10 = 0 then r:= r/10^padic:-ordp(r, 5) fi;

  if r mod 10 = 8 then count:= count+1; A[count]:= n fi;

od:

seq(A[i], i=1..100); # Robert Israel, Dec 16 2016

MATHEMATICA

Select[Range[5, 250], Last[Flatten[Most[Split[IntegerDigits[#!]]]]]==8&] (* Harvey P. Dale, Jun 11 2014 *)

f[n_] := Mod[6 Times @@ (Rest[ FoldList[{1 + #1[[1]], #2! 2^(#1[[1]] #2)} &, {0, 0}, Reverse[ IntegerDigits[n, 5]]]]), 10][[2]] (* after Jacob A. Siehler & Greg Dresden in A008904 *); f[0] = f[1] = 1; Select[ Range[150], f[#] == 8 &] (* Robert G. Wilson v, Dec 28 2016 *)

CROSSREFS

Cf. A008904, A045547, A045548, A045549.

Sequence in context: A253881 A097480 A034068 * A031047 A120193 A134534

Adjacent sequences:  A045547 A045548 A045549 * A045551 A045552 A045553

KEYWORD

nonn,base

AUTHOR

Jeff Burch

STATUS

approved

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Last modified June 28 07:25 EDT 2022. Contains 354903 sequences. (Running on oeis4.)