A045560 - OEIS

A045560

Numbers whose factorial has '48' as its final two digits before the trailing zeros.

30, 77, 81, 142, 154, 157, 190, 245, 248, 267, 311, 332, 345, 348, 370, 373, 395, 398, 403, 427, 433, 444, 475, 476, 508, 519, 553, 562, 567, 584, 591, 618, 643, 658, 669, 682, 696, 727, 730, 750, 751, 796, 811

(list; graph; refs; listen; history; text; internal format)

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)==48 \\ 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==48 \\ 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==48, listput(v, n); if(#v==100, return(Vec(v))))) \\ Charles R Greathouse IV, Oct 22 2014

CROSSREFS

Sequence in context: A179321 A039517 A185479 * A159219 A098998 A044168

Adjacent sequences: A045557 A045558 A045559 * A045561 A045562 A045563

KEYWORD

nonn,base

AUTHOR

Jeff Burch

STATUS

approved