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 A257794 #9 Jun 02 2025 11:47:23 %S A257794 2,4,1,8,6,12,9,16,18,11,22,24,14,28,17,32,34,36,20,40,23,44,46,48,26, %T A257794 52,29,56,58,31,62,64,35,68,70,72,38,76,41,80,82,43,86,88,47,92,94,96, %U A257794 50,100,53,104,106,55,110,112,59,116,118,61,122,124,65,128 %N A257794 Lexicographically earliest injective sequence such that a(n) divides a(a(n)). %C A257794 "Lexicographically earliest injective sequence" means that a(n+1) is the least positive integer not occurring earlier with the given property. %C A257794 For n>3 it appears that a(n) is either 2*n, n+1 or n+2. %H A257794 Lars Blomberg, <a href="/A257794/b257794.txt">Table of n, a(n) for n = 1..9999</a> %H A257794 E. Angelini, <a href="https://web.archive.org/web/*/http://list.seqfan.eu/oldermail/seqfan/2015-April/014685.html">a(n) divides a(a(n))</a>, Seqfan (Apr 11 2015) %e A257794 a(1)=2, a(a(1))=a(2)=4, and 2 divides 4. %e A257794 a(8)=16, a(a(8))=a(16)=32, and 8 divides 32. %K A257794 nonn %O A257794 1,1 %A A257794 _Eric Angelini_ and _Lars Blomberg_, May 11 2015