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 A275610 #19 Dec 12 2016 09:00:19 %S A275610 0,1,2,3,4,5,6,0,7,0,8,0,9,0,10,0,11,0,12,13,14,0,15,16,0,17,18,0,19, %T A275610 20,0,21,22,0,23,24,0,25,0,26,27,28,0,29,30,31,0,32,33,34,0,35,36,37, %U A275610 0,38,39,40,0,41,42,0,43,44,0,45,0,46,47,0,48,0,49,50,0,51,0,52,53,0,54,0,55,56,0,57,0,58,59,0,60 %N A275610 Hexagonal spiral constructed on the nodes of the triangular net in which every 1 of A275606 is replaced with the least positive integer not yet in the sequence. %C A275610 A way for the enumeration of the nodes of the hexagonal net. %C A275610 Also a way for the enumeration of the atoms of carbon in graphene. %C A275610 Also sequence in which every positive integer of A274920 is replaced with the least positive integer not yet in the sequence. %H A275610 Wikipedia, <a href="http://en.wikipedia.org/wiki/Graphene">Graphene</a> %e A275610 Illustration of initial terms as a spiral: %e A275610 . %e A275610 . 9 - 0 - 8 %e A275610 . / \ %e A275610 . 0 3 - 2 0 %e A275610 . / / \ \ %e A275610 . 10 4 0 - 1 7 %e A275610 . \ \ / %e A275610 . 0 5 - 6 - 0 %e A275610 . \ %e A275610 . 11 - 0 - 12 %e A275610 . %Y A275610 Cf. A274820, A274821, A274920, A274921, A275606. %K A275610 nonn %O A275610 0,3 %A A275610 _Omar E. Pol_, Aug 03 2016