A279688 Numbers k such that k and 2k are anagrams in some base.

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

Offset

1,2

Links

Chai Wah Wu, Table of n, a(n) for n = 1..10001

Example

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.

Mathematica

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 *)

Prog

(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

Crossrefs

Cf. A023094.

Sequence in context: A031258 A277557 A108060 * A178180 A269311 A242185

Adjacent sequences: A279685 A279686 A279687 * A279689 A279690 A279691

Keyword

nonn,base,look

Author

Peter Kagey, Dec 17 2016

Status

approved