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A072199 a(n)-th factorial is the smallest factorial containing exactly n 5's, or 0 if no such number exists. 8
7, 17, 25, 30, 37, 41, 43, 46, 75, 65, 55, 83, 74, 80, 94, 116, 91, 114, 131, 111, 115, 136, 147, 125, 128, 143, 102, 169, 152, 157, 197, 150, 165, 185, 193, 190, 206, 198, 192, 214, 236, 203, 242, 226, 205, 256, 251, 220, 270, 239, 230, 261, 286, 222, 264 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..55.

EXAMPLE

a(2)=17 since 17th factorial, i.e., 17!=355687428096000 contains exactly two 5's.

MATHEMATICA

Do[k = 1; While[ Count[IntegerDigits[k! ], 5] != n, k++ ]; Print[k], {n, 1, 60}]

With[{fs=Table[{n, n!}, {n, 500}]}, Table[SelectFirst[fs, DigitCount[#[[2]], 10, 5] == k&], {k, 100}]][[All, 1]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Dec 16 2018 *)

CROSSREFS

Cf. A072242, A072220, A072208, A072204, A072200, A072178, A072177, A072163 & A072124.

Sequence in context: A300298 A273745 A263264 * A309231 A183897 A300186

Adjacent sequences:  A072196 A072197 A072198 * A072200 A072201 A072202

KEYWORD

base,nonn

AUTHOR

Shyam Sunder Gupta, Jul 30 2002

EXTENSIONS

Edited and extended by Robert G. Wilson v, Jul 31 2002

STATUS

approved

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Last modified July 28 14:19 EDT 2021. Contains 346335 sequences. (Running on oeis4.)