A272215 a(n) = that number formed by permuting the digits of n which is divisible by the highest power of 2 (in case of a tie, choose the smallest number).
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 12, 22, 32, 24, 52, 26, 72, 28, 92, 30, 13, 32, 33, 34, 35, 36, 37, 38, 39, 40, 14, 24, 34, 44, 54, 64, 74, 48, 94, 50, 15, 52, 35, 54, 55, 56, 57, 58, 59, 60, 16, 26, 36, 64, 56, 66, 76, 68, 96, 70, 17, 72, 37, 74, 57, 76, 77, 78, 79, 80, 18, 28, 38
Offset: 1
Examples
The numbers obtained by permuting the digits of 1336 are 1336, 1363, 1633, 3136, 3163, 6133, 3316, 3613, 6313, 3361, 3631 and 6331. The highest power of 2 dividing any of these is 2^6, which divides just one of them, 3136, so a(1336) = 3136.
Links
- David A. Corneth, Table of n, a(n) for n = 1..10000
Programs
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Mathematica
hp2[n_]:=Module[{c={#,IntegerExponent[#,2]}&/@(FromDigits/@ Permutations[ IntegerDigits[ n]]),mx},mx=Max[c[[All,2]]];Min[Select[c,#[[2]]==mx&][[All,1]]]]; Array[hp2,90] (* Harvey P. Dale, Jan 27 2020 *)
Comments