A045555 Numbers whose factorial has '24' as its final two digits before the trailing zeros.

4, 37, 49, 52, 58, 69, 75, 76, 87, 117, 179, 205, 277, 289, 307, 321, 339, 383, 394, 409, 411, 416, 425, 426, 461, 468, 493, 512, 546, 563, 621, 645, 648, 717, 724, 725, 726, 759, 760, 766, 780, 807, 821, 827, 831

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)==24 \\ 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==24 \\ 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==24, listput(v, n); if(#v==100, return(Vec(v))))) \\ Charles R Greathouse IV, Oct 22 2014

Crossrefs

Sequence in context: A222517 A103369 A031189 * A297803 A183378 A145401

Adjacent sequences: A045552 A045553 A045554 * A045556 A045557 A045558

Keyword

nonn,base

Author

Jeff Burch

Status

approved