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 A351406 #27 Feb 13 2022 14:00:15 %S A351406 0,123,1,23,2,13,3,12,4,17,5,34,6,39,7,14,8,79,9,36,10,32,11,112,15, %T A351406 114,16,119,18,159,19,116,20,31,21,27,22,35,24,57,25,47,26,97,28,1199, %U A351406 29,43,30,45,33,141,37,158,38,139,40,53,41,70,42,75,44,709,46 %N A351406 For all a(2n) the cumulative sum of the odd digits used so far in the sequence [including a(2n)] is twice the cumulative sum of the even digits used so far in the sequence [including a(2n)]. This is the lexicographically earliest sequence of distinct numbers >= 0 with this property. %C A351406 The sequence is a permutation of the nonnegative integers. %H A351406 Carole Dubois, <a href="/A351406/b351406.txt">Table of n, a(n) for n = 1..10000</a> %H A351406 Eric Angelini, <a href="http://cinquantesignes.blogspot.com/2022/02/une-merveille-avec-a2n.html">Une merveille avec a(2n)</a>, Feb 8, 2022, personal blog (in French). %H A351406 Carole Dubois, <a href="/A351406/a351406.jpg">Comparative graphs for A351406 and A351378</a> %H A351406 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %e A351406 This sequence : 0, 123, 1, 23, 2, 13, 3, 12, 4, 17, 5, 34, 6, 39, 7, 14, 8, ... %e A351406 Even dig. sums: 0, 2, 2, 4, 6, 6, 6, 8, 12, 12, 12, 16, 22, 22, 22, 26, 34, ... %e A351406 Odd dig. sums : 0, 4, 5, 8, 8, 12, 15, 16, 16, 24, 29, 32, 32, 44, 51, 52, 52, ... %e A351406 x x x x x x x x ... %e A351406 We see that 4 is twice 2, 8 is twice 4, 12 is twice 6, 16 is twice 8, 24 is twice 12, etc. %Y A351406 Cf. A001477, A036301, A351378. %K A351406 nonn,base,look %O A351406 1,2 %A A351406 _Eric Angelini_ and _Carole Dubois_, Feb 10 2022