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 A338221 #14 Feb 01 2021 15:43:32 %S A338221 1,2,4,3,6,5,10,7,8,16,12,20,40,24,9,18,36,30,15,45,90,50,14,28,32,64, %T A338221 48,60,80,120,240,160,72,27,54,108,216,144,150,25,75,180,360,270,100, %U A338221 42,21,63,126,252,84,96,192,320,480,720,1440,288,576,432,81,162 %N A338221 Square spiral of distinct positive integers built by greedy algorithm such that each new value (except the initial one) is a divisor or a multiple of some earlier horizontally or vertically adjacent value. %C A338221 This sequence has similarities with A113552 and A282291, as each term is adjacent to one of its divisors or multiples. %H A338221 Rémy Sigrist, <a href="/A338221/b338221.txt">Table of n, a(n) for n = 0..10200</a> %H A338221 Rémy Sigrist, <a href="/A338221/a338221.png">Colored representation of the spiral for -500 <= x, y <= 500</a> (where the color is function of a(n)) %H A338221 Rémy Sigrist, <a href="/A338221/a338221_1.png">Colored representation of the spiral for -500 <= x, y <= 500</a> (where the color is function of A006530(a(n))) %H A338221 Rémy Sigrist, <a href="/A338221/a338221.gp.txt">PARI program for A338221</a> %e A338221 The spiral begins: %e A338221 216--108---54---27---72--160--240 %e A338221 | | %e A338221 144 36---18----9---24---40 120 %e A338221 | | | | %e A338221 150 30 6----3----4 20 80 %e A338221 | | | | | | %e A338221 25 15 5 1----2 12 60 %e A338221 | | | | | %e A338221 75 45 10----7----8---16 48 %e A338221 | | | %e A338221 180 90---50---14---28---32---64 %e A338221 | %e A338221 360--270--100---42---21---63--126 %o A338221 (PARI) See Links section. %Y A338221 Cf. A006530, A113552, A282291. %K A338221 nonn,look %O A338221 0,2 %A A338221 _Rémy Sigrist_, Jan 30 2021