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A279688
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Numbers k such that k and 2k are anagrams in some base.
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3
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0, 8, 18, 21, 27, 32, 40, 48, 65, 66, 72, 78, 86, 96, 98, 99, 104, 108, 111, 114, 123, 133, 168, 176, 189, 190, 200, 208, 225, 240, 248, 258, 260, 264, 266, 270, 280, 288, 294, 296, 297, 312, 314, 318, 320, 330, 341, 350, 363, 380, 387, 396, 399, 408, 429, 432
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OFFSET
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1,2
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LINKS
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EXAMPLE
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a(2) = 8 because in base 5, 8 = 13_5 and 16 = 31_5.
a(3) = 18 because in base 4, 18 = 102_4 and 36 = 210_4.
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MATHEMATICA
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fQ[n_] := Block[{b = 2}, While[ 2b < n +3 && Sort[ IntegerDigits[n, b]] != Sort[ IntegerDigits[ 2n, b]], b++]; 2b < n +3]; fQ[0] = True; Select[Range[0, 435], fQ] (* Robert G. Wilson v, Dec 21 2016 *)
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PROG
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(PARI) isok(n) = if (n==0, 1, for (b=2, n, if (vecsort(digits(n, b)) == vecsort(digits(2*n, b)), return(1))); 0); \\ Michel Marcus, Dec 17 2016
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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