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A066460
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a(n) is the least positive integer k such that k is a repdigit number in exactly n different bases B, where 1<B<k.
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1
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2, 3, 7, 15, 24, 40, 60, 144, 120, 180, 336, 420, 360, 900, 960, 720, 840, 1260, 1440, 2340, 1680, 2880, 3600, 8190, 2520, 9072, 9900, 6300, 6720, 20592, 5040, 10920, 7560, 31320, 98040, 25920, 10080, 21420, 177156, 74256, 15120, 28560, 20160
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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COMMENTS
| All numbers, n, are repdigit in base 1 and in all bases greater than n, therefore we restrict our sequence to bases between 1 and n exclusively.
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EXAMPLE
| a(4) = 24 since 24_10 = 44_5 = 33_7 = 22_11 = 11_23.
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MATHEMATICA
| a = Table[0, {50} ]; Do[c = 0; k = 2; While[k < n, If[ Length[ Union[ IntegerDigits[n, k]]] == 1, c++ ]; k++ ]; If[ a[[c]] == 0, a[[c]] = n], {n, 2, 25000} ]; a
Do[ c = 1; k = 2; While[ k < n-1, If[ Length[ Union[ IntegerDigits[n, k]]] == 1, c++ ]; k++ ]; If[a[[c]] == 0, a[[c]] = n; Print[c, " = ", n]], {n, 1, 200000} ]
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CROSSREFS
| Cf. A066044.
Sequence in context: A068080 A098763 A066044 * A001276 A006884 A074742
Adjacent sequences: A066457 A066458 A066459 * A066461 A066462 A066463
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KEYWORD
| nonn
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AUTHOR
| Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 02 2002
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EXTENSIONS
| Edited by John W. Layman (layman(AT)math.vt.edu), Jan 16 2002
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