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Search: id:A072220
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| A072220 |
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a(n)-th factorial is the smallest factorial containing exactly n 9's, or 0 if no such number exists. |
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+0
9
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| 12, 11, 21, 29, 34, 46, 36, 59, 79, 75, 0, 70, 82, 90, 95, 97, 112, 89, 105, 96, 134, 130, 127, 165, 142, 149, 144, 145, 161, 163, 182, 189, 160, 178, 139, 180, 206, 192, 224, 214, 188, 215, 226, 207, 218, 267, 283, 261, 268, 262, 240, 280, 234, 285, 343, 277
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OFFSET
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1,1
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COMMENT
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It is conjectured that a(11)=0 since no factorial < 10000 contained just eleven nines.
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EXAMPLE
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a(2)=11 since 11-th factorial i.e. 11!=39916800 contains exactly two 9's.
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MATHEMATICA
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Do[k = 1; While[ Count[IntegerDigits[k! ], 9] != n, k++ ]; Print[k], {n, 1, 60}]
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CROSSREFS
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Cf. A072232, A072208, A072204, A072200, A072199, A072178, A072177, A072163 & A072124.
Adjacent sequences: A072217 A072218 A072219 this_sequence A072221 A072222 A072223
Sequence in context: A070560 A019330 A086045 this_sequence A038337 A125509 A097824
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KEYWORD
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base,nonn
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AUTHOR
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Shyam Sunder Gupta (guptass(AT)rediffmail.com), Jul 30 2002
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EXTENSIONS
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Edited and extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Jul 31 2002
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