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A072163 a(n)-th factorial is the smallest factorial containing exactly n 2's, or 0 if no such number exists. 8
2, 14, 13, 30, 40, 47, 31, 46, 54, 49, 65, 76, 62, 69, 107, 78, 86, 115, 95, 121, 109, 165, 110, 113, 149, 151, 146, 137, 162, 159, 170, 191, 195, 174, 190, 196, 164, 209, 202, 173, 198, 248, 201, 262, 231, 205, 263, 233, 246, 256, 270, 244, 287, 200, 271, 250 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..56.

EXAMPLE

a(2)=14 since 14th factorial, i.e., 14!=87178291200, contains exactly two 2's.

MATHEMATICA

Do[k = 1; While[ Count[IntegerDigits[k! ], 2] != n, k++ ]; Print[k], {n, 1, 60}]

CROSSREFS

Cf. A072293, A072220, A072208, A072204, A072200, A072199, A072178, A072177, A072124.

Sequence in context: A158787 A174706 A307269 * A084674 A009774 A276553

Adjacent sequences:  A072160 A072161 A072162 * A072164 A072165 A072166

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 September 27 17:05 EDT 2021. Contains 347693 sequences. (Running on oeis4.)