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 A330623 #9 Dec 26 2019 05:44:42 %S A330623 1,1,2,2,3,2,2,3,3,4,4,2,4,3,3,5,3,3,4,4,5,4,4,2,5,6,2,5,6,3,6,4,3,6, %T A330623 6,5,4,4,3,4,5,5,6,7,5,4,4,6,4,4,7,5,5,6,5,6,7,8,4,5,7,7,6,7,8,6,3,6, %U A330623 7,8,5,5,8,3,6,9,5,8,7,5,9,7,7,8,6,5,8 %N A330623 Lexicographically earliest sequence of positive terms such that for any n > 0 and k > 0, a(n+2*k) <> gcd(a(n), a(n+k)). %C A330623 This sequence differs radically from the variant where we consider nonnegative terms (A330622). %H A330623 Rémy Sigrist, <a href="/A330623/b330623.txt">Table of n, a(n) for n = 1..10000</a> %H A330623 Rémy Sigrist, <a href="/A330623/a330623.png">Scatterplot of the first 250000 terms</a> %H A330623 Rémy Sigrist, <a href="/A330623/a330623.txt">C program for A330623</a> %o A330623 (C) See Links section. %Y A330623 Cf. A330622 (nonnegative variant). %Y A330623 See A330267 for similar sequences. %K A330623 nonn %O A330623 1,3 %A A330623 _Rémy Sigrist_, Dec 21 2019