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A045561 Numbers n such that final 2 nonzero digits of n! are '52'. 1
34, 36, 41, 86, 93, 122, 132, 150, 151, 167, 177, 183, 194, 249, 257, 342, 349, 374, 399, 421, 440, 479, 511, 515, 522, 557, 571, 580, 606, 631, 665, 678, 687, 692, 734, 738, 741, 754, 778, 867, 895, 898, 912, 924, 931, 939, 950, 951, 962, 975, 976, 1012 (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

MATHEMATICA

Select[Range[5, 1100], Take[Flatten[Most[Split[IntegerDigits[#!]]]], -2] == {5, 2}&] (* Harvey P. Dale, Aug 08 2016 *)

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)==52 \\ 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==52 && n>2 \\ Charles R Greathouse IV, Oct 22 2014

(PARI) v=List(); m=Mod(6, 25); for(n=4, 1e6, m*=n/10^valuation(n, 5); if(m==52, listput(v, n); if(#v==100, return(Vec(v))))) \\ Charles R Greathouse IV, Oct 22 2014

CROSSREFS

Sequence in context: A203462 A270311 A257315 * A067190 A218006 A250738

Adjacent sequences:  A045558 A045559 A045560 * A045562 A045563 A045564

KEYWORD

nonn,base

AUTHOR

Jeff Burch

EXTENSIONS

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

STATUS

approved

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Last modified October 20 15:41 EDT 2017. Contains 293622 sequences.