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 A374991 #6 Jul 28 2024 10:07:18 %S A374991 0,1,2,3,4,7,6,11,5,10,8,13,16,15,12,19,9,18,36,32,22,26,23,14,28,31, %T A374991 24,29,46,58,47,20,37,41,74,72,39,25,38,50,76,51,102,103,57,48,54,27, %U A374991 44,52,75,82,64,42,21,43,53,86,40,45,80,89,77,144,79,60,30 %N A374991 Lexicographically earliest sequence of distinct nonnegative integers such that the concatenation of the binary expansions of two consecutive terms, in at least one way, and after removal of trailing digits, is palindromic. %H A374991 Rémy Sigrist, <a href="/A374991/a374991.gp.txt">PARI program</a> %e A374991 The first terms, in decimal and in binary, alongside an appropriate palindrome (with dots denoting the removed trailing zeros), are: %e A374991 n a(n) bin(a(n)) palindrome %e A374991 -- ---- --------- ---------- %e A374991 0 0 0 1 %e A374991 1 1 1 11. %e A374991 2 2 10 111. %e A374991 3 3 11 111.. %e A374991 4 4 100 1111.. %e A374991 5 7 111 11111. %e A374991 6 6 110 1101011 %e A374991 7 11 1011 1011101 %e A374991 8 5 101 101101. %e A374991 9 10 1010 10101... %e A374991 10 8 1000 11011... %e A374991 11 13 1101 11011.... %e A374991 12 16 10000 11111.... %o A374991 (PARI) \\ See Links section. %Y A374991 Cf. A000975, A057890, A374990. %K A374991 nonn,base %O A374991 0,3 %A A374991 _Rémy Sigrist_, Jul 26 2024