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 A336200 #12 Jul 14 2020 21:40:35 %S A336200 1,1,2,2,3,4,3,4,5,6,8,5,7,6,8,7,9,10,11,12,13,9,14,10,12,15,11,13,14, %T A336200 16,17,18,19,15,20,21,16,23,22,17,24,18,25,19,26,27,20,22,21,28,24,23, %U A336200 29,30,25,31,27,32,33,26,35,34,28,36,38,37,29,39,40,30 %N A336200 Lexicographically earliest sequence of distinct terms such that every integer k appears twice, at distance a(k). %C A336200 This sequence combines features of A001462 and of A026242. %H A336200 Rémy Sigrist, <a href="/A336200/b336200.txt">Table of n, a(n) for n = 1..10000</a> %H A336200 Rémy Sigrist, <a href="/A336200/a336200.gp.txt">PARI program for A336200</a> %e A336200 For n = 1: %e A336200 - we can choose a(1) = 1, %e A336200 - and then a(1+a(1)) = a(2) = 1. %e A336200 For n = 3: %e A336200 - we can choose a(3) = 2, %e A336200 - and then a(3+a(2)) = a(4) = 2. %e A336200 For n = 5: %e A336200 - we can choose a(5) = 3, %e A336200 - and then a(5+a(3)) = a(7) = 3. %o A336200 (PARI) See Links section. %Y A336200 Cf. A001462, A026242. %K A336200 nonn %O A336200 1,3 %A A336200 _Rémy Sigrist_, Jul 11 2020