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Search: id:A072163
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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. +0
9
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; listen)
OFFSET

1,1

EXAMPLE

a(2)=14 since 14-th 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: A084677 A082609 A158787 this_sequence A084674 A009774 A032933

Adjacent sequences: A072160 A072161 A072162 this_sequence A072164 A072165 A072166

KEYWORD

base,nonn

AUTHOR

Shyam Sunder Gupta (guptass(AT)rediffmail.com), Jul 30 2002

EXTENSIONS

Edited and extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Jul 31 2002

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.


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