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 A307190 #13 Mar 31 2019 17:27:10 %S A307190 2,5,8,15,21,26,28,31,36,39,41,46,48,55,60,73,75,82,84,86,91,93,98, %T A307190 101,104,106,108,110,116,118,120,129,131,138,143,159,161,170,172,174, %U A307190 176,183,185,187,192,197,199,202,204,206,208,211,218,220,222,224,235 %N A307190 Positions of 2's in the square spiral in A275609. %H A307190 Alois P. Heinz, <a href="/A307190/b307190.txt">Table of n, a(n) for n = 1..20000</a> (first 1216 terms from N. J. A. Sloane) %H A307190 Rémy Sigrist, <a href="/A307190/a307190.png">Colored scatterplot of (x,y) such that A275609(x,y) = 2 and -500 <= x <= 500 and -500 <= y <= 500</a> (where the color is function of (x mod 2) + 2 * (y mod 2)) %Y A307190 Cf. A275609, A307188-A307192. %K A307190 nonn %O A307190 1,1 %A A307190 _N. J. A. Sloane_, Mar 28 2019