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 A363938 #24 Jul 11 2023 13:41:25 %S A363938 1,2,3,4,5,6,7,9,11,13,8,17,15,19,12,23,25,29,10,31,14,27,16,21,37,33, %T A363938 26,41,22,35,43,47,18,49,24,53,39,20,51,55,28,59,61,32,45,34,67,57,40, %U A363938 63,71,36,65,38,73,79,30,83,77,46,89,69,91,58,81,85,87 %N A363938 Lexicographically earliest sequence of numbers in a hexagonal spiral such that their neighbors have no common prime factor. %H A363938 Carole Dubois, <a href="/A363938/b363938.txt">Table of n, a(n) for n = 1..4999</a> %H A363938 Carole Dubois, <a href="/A363938/a363938.jpg">Hexagonal spiral for A363938</a>. %H A363938 Carole Dubois, <a href="/A363938/a363938_1.jpg">Scatterplot of A363938(n)</a> %H A363938 Carole Dubois, <a href="/A363938/a363938_2.jpg">Hexagons with spiral</a> %e A363938 a(11) = 8 because the neighbors of the 11th hexagon are 3, 13, 17, 21, 33, 37, which do not have any common prime divisor with 8. %Y A363938 Cf. A000384, A003458, A014105, A056105, A363765. %K A363938 nonn %O A363938 1,2 %A A363938 _Carole Dubois_, Jun 29 2023