A045565 Numbers whose factorial has '72' as its final two digits before the trailing zeros.

6, 40, 53, 62, 67, 109, 113, 116, 146, 162, 174, 200, 201, 212, 237, 271, 278, 305, 362, 392, 438, 471, 495, 498, 531, 583, 594, 709, 716, 735, 740, 770, 773, 805, 828, 850, 851, 882, 967, 974, 999, 1000, 1001, 1059, 1066, 1072, 1082, 1095, 1098, 1107, 1143

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)==72 \\ 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==72 \\ 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==72, listput(v, n); if(#v==100, return(Vec(v))))) \\ Charles R Greathouse IV, Oct 22 2014

Crossrefs

Sequence in context: A145001 A263955 A108937 * A334903 A200945 A217074

Adjacent sequences: A045562 A045563 A045564 * A045566 A045567 A045568

Keyword

nonn,base

Author

Jeff Burch

Extensions

More terms from Robert G. Wilson v, Dec 14 2000

Status

approved