A231926 Working in base 6: a(0)=0, thereafter a(n+1) is the smallest number not already in the sequence such that the bits of a(n) and a(n+1) together can be rearranged to form a palindrome.

0, 11, 1, 10, 100, 12, 2, 20, 101, 22, 3, 13, 31, 103, 30, 110, 33, 4, 14, 41, 104, 40, 114, 24, 42, 112, 21, 102, 120, 201, 210, 1000, 105, 15, 5, 25, 52, 115, 35, 53, 113, 23, 32, 121, 44, 55, 111, 51, 122, 133, 144, 155, 212, 221, 313, 331, 414, 441, 515, 551, 1001

Offset

0,2

Comments

This is a permutation of the nonnegative integers in base 6 - see the Comments in A228407 for the proof.

Links

Table of n, a(n) for n=0..60.

Mathematica

a[0] = 0; a[n_] := a[n] = Block[{k = 1, idm = IntegerDigits[ a[n - 1], 6], t = a@# & /@ Range[n - 1]}, Label[ start]; While[ MemberQ[t, k], k++];  While[ Select[ Permutations[ Join[ idm, IntegerDigits[k, 6]]], #[[1]] != 0 && # == Reverse@# &] == {}, k++; Goto[ start]]; k]; s = Array[a, 60, 0]; FromDigits@# & /@ IntegerDigits[s, 6]

Crossrefs

Cf. A230891, A231920, A231922, A231924, A231928, A231930, A231932, A228407, A231927.

Sequence in context: A231928 A231930 A231932 * A231924 A231922 A231920

Adjacent sequences: A231923 A231924 A231925 * A231927 A231928 A231929

Keyword

nonn,base,easy

Author

N. J. A. Sloane and Robert G. Wilson v, Nov 15 2013

Status

approved