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 A220100 #11 Aug 13 2018 09:12:26 %S A220100 18,27,26,42,42,34,35,42,42,74,74,58,58,66,66,106,106,82,82,90,90,98, %T A220100 98,106,106,154,154,122,122,130,130,138,138,146,146,202,202,162,162, %U A220100 170,170,178,178,186,186,194,194,202,202,266,266,218,218,226,226,234,234,242 %N A220100 Sum of the four nearest neighbors of n in a double spiral with positive integers and 1 at the center. %C A220100 Double spiral begins: %C A220100 . %C A220100 82---84---86---88---90---92---94---96---98 %C A220100 | %C A220100 80 51---53---55---57---59---61---63---65 %C A220100 | | | %C A220100 78 49 26---28---30---32---34---36 67 %C A220100 | | | | | %C A220100 76 47 24 11---13---15---17 38 69 %C A220100 | | | | | | | %C A220100 74 45 22 9 2----4 19 40 71 %C A220100 | | | | | | | | | %C A220100 72 43 20 7 1 6 21 42 73 %C A220100 | | | | | | | | | %C A220100 70 41 18 5----3 8 23 44 75 %C A220100 | | | | | | | %C A220100 68 39 16---14---12---10 25 46 77 %C A220100 | | | | | %C A220100 66 37---35---33---31---29---27 48 79 %C A220100 | | | %C A220100 64---62---60---58---56---54---52---50 81 %C A220100 | %C A220100 99---97---95---93---91---89---87---85---83 %e A220100 The four nearest neighbors of 8 are 3, 6, 23, 10; their sum is a(8)=42. %e A220100 The four nearest neighbors of 9 are 22, 11, 2, 7; their sum is a(9)=42. %Y A220100 Cf. A220098, A220099. %K A220100 nonn,easy %O A220100 1,1 %A A220100 _Alex Ratushnyak_, Dec 04 2012