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A187713
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Base-5 Keith numbers.
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8
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5, 9, 10, 11, 13, 15, 20, 22, 31, 40, 43, 53, 62, 71, 84, 93, 124, 154, 221, 483, 3044, 18748, 125973, 232085, 1705260, 2091605, 5616236, 8067806, 8849508, 58944155, 84572166, 164487062, 421825427, 469435978, 744740232
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OFFSET
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1,1
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COMMENTS
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Among bases b = 2 to 36, in b = 5 there is the third highest percentage of Keith numbers between b and b^3 (that is, numbers with two or three digits); only binary and ternary have more Keith numbers in that range.
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LINKS
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EXAMPLE
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a(2) = 9. In base 5, the number 9 is written 14, and the second order linear recurrence is then 1, 4, 5, 9, ... therefore 9 is a Keith number in base 5.
The number 14 is a Keith number in base 10 but not base 5, as we have: 2, 4, 6, 10, 16, ...
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MATHEMATICA
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(* First run the program for A186830 to define keithSeq *) Select[Range[5, 10^6], Last[keithSeq[#, 5]] == # &]
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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