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URL: https://oeis.org/A045565

⇱ A045565 - OEIS

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A045565
Numbers whose factorial has '72' as its final two digits before the trailing zeros.
1
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
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
KEYWORD
nonn,base
AUTHOR
EXTENSIONS
More terms from Robert G. Wilson v, Dec 14 2000
STATUS
approved