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 A338047 #10 Oct 18 2020 22:32:02 %S A338047 0,1,2,4,8,9,11,16,17,18,21,22,32,33,34,35,36,37,38,39,42,43,44,45,46, %T A338047 48,52,64,65,66,68,69,72,73,75,77,79,80,81,82,85,92,93,95,98,126,128, %U A338047 129,130,131,132,133,134,135,136,138,140,142,143,144,145,147 %N A338047 Lexicographically earliest sequence of nonnegative integers such that for any n >= 0, a(n) does not appear in the XOR-triangle with bottom row (a(0), ..., a(n-1)). %C A338047 All powers of 2 appear in the sequence. %H A338047 Rémy Sigrist, <a href="/A338047/b338047.txt">Table of n, a(n) for n = 0..8191</a> %H A338047 Rémy Sigrist, <a href="/A338047/a338047.gp.txt">PARI program for A338047</a> %e A338047 The first terms, alongside the corresponding XOR-triangle, are: %e A338047 6 %e A338047 2 4 %e A338047 17 19 23 %e A338047 29 12 31 8 %e A338047 1 28 16 15 7 %e A338047 0 1 29 13 2 5 %e A338047 8 8 9 20 25 27 30 %e A338047 7 15 7 14 26 3 24 6 %e A338047 2 5 10 13 3 25 26 2 4 %e A338047 1 3 6 12 1 2 27 1 3 7 %e A338047 a(n)| 0 1 2 4 8 9 11 16 17 18 21 %e A338047 ----+---------------------------------------------------------------------------- %e A338047 n | 0 1 2 3 4 5 6 7 8 9 10 %o A338047 (PARI) See Links section. %Y A338047 Cf. A001651 (additive analog), A003987. %K A338047 nonn,base %O A338047 0,3 %A A338047 _Rémy Sigrist_, Oct 08 2020