This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A231927 #7 Nov 16 2013 14:15:57
%S A231927 0,7,1,6,36,8,2,12,37,14,3,9,19,39,18,42,21,4,10,25,40,24,46,16,26,44,
%T A231927 13,38,48,73,78,216,41,11,5,17,32,47,23,33,45,15,20,49,28,35,43,31,50,
%U A231927 57,64,71,80,85,117,127,154,169,191,211,217,55,22,27,58,63,118,133
%N A231927 Terms of A231926 written in base 10: the binary expansions of a(n) and a(n+1) taken together can be rearranged to form a palindrome.
%C A231927 See A231926 for precise definition.
%C A231927 This is a permutation of the nonnegative integers - see the Comments in A228407 for the proof.
%t A231927 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]
%Y A231927 Cf. A230892, A231921, A231923, A231925, A231929, A231931, A231933, A228407, A231926.
%K A231927 nonn,base,easy
%O A231927 0,2
%A A231927 _N. J. A. Sloane_ and _Robert G. Wilson v_, Nov 15 2013