A045552 Numbers whose factorial has '08' as its final two digits before the trailing zeros.

13, 80, 108, 114, 119, 137, 185, 193, 207, 220, 223, 246, 262, 315, 346, 371, 396, 400, 401, 417, 431, 439, 487, 506, 535, 550, 551, 585, 597, 609, 613, 616, 634, 635, 641, 656, 679, 708, 719, 767, 779, 782, 815

Offset

1,1

Links

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Index entries for sequences related to final digits of numbers

Prog

(PARI) last(n, k)=if(n*8\9-1<k, n=n!; return(n/10^valuation(n, 10)%10^k)); my(m=Mod(1, 5^k)); for(i=2, n, m*=i/10^valuation(i, 5)); lift(chinese(m, Mod(0, 2^k))) \\ Gives the last k decimal digits of n!.
is(n)=last(n, 2)==8 \\ Charles R Greathouse IV, Oct 22 2014
(PARI) is(n)=my(m=Mod(1, 25)); for(i=2, n, m*=i/10^valuation(i, 5)); m==8 \\ Charles R Greathouse IV, Oct 22 2014
(PARI) v=List(); m=Mod(1, 25); for(n=2, 1e6, m*=n/10^valuation(n, 5); if(m==8, listput(v, n); if(#v==100, return(Vec(v))))) \\ Charles R Greathouse IV, Oct 22 2014

Crossrefs

Sequence in context: A236952 A136373 A071614 * A264381 A339851 A297678

Adjacent sequences: A045549 A045550 A045551 * A045553 A045554 A045555

Keyword

nonn,base

Author

Jeff Burch

Status

approved