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 A257332 #11 Apr 30 2015 20:04:51 %S A257332 7,9,23,15,14,47,12,59,22,65,83,26,97,101,103,119,81,137,133,143,149, %T A257332 93,161,48,179,42,191,54,199,129,217,66,233,56,247,82,257,271,88,283, %U A257332 92,183,98,305,104,319,325,329,335,231,353,355,373,377,118,383,401 %N A257332 Construct spiral of numbers on square grid as in Comments; sequence gives terms along the "7" arm. %C A257332 Place numbers 2,3,5,7 clockwise around a grid point (see illustrations in links). Divide grid into four spiral arms. %C A257332 Extend each arm one step at a time, in rotation: first the 2 arm, then the 3 arm, then the 5 arm, then the 7 arm, then the 2 arm, etc. %C A257332 Rule for extending: next term in arm is smallest number such that each cell in the grid is relatively prime to its eight neighbors. Every term in the entire grid must be different. %C A257332 The four arms are A257329, A257330, A257331, A257332. %C A257332 Conjecture: every number > 1 appears in one of the four arms. %H A257332 Lars Blomberg, <a href="/A257332/b257332.txt">Table of n, a(n) for n = 1..10000</a> %H A257332 Popular Computing (Calabasas, CA), <a href="/A257321/a257321.png">Problem 146: Gcd</a>, Vol. 4 (No. 45, Dec 1976), page PC45-4. %H A257332 N. J. A. Sloane, <a href="/A257321/a257321_1.png">Spirals showing initial terms of A257321-A257332</a> %Y A257332 Cf. A064413, A257321-A257340, A257347 (the union list). %K A257332 nonn %O A257332 1,1 %A A257332 _N. J. A. Sloane_, Apr 21 2015 %E A257332 More terms from _Lars Blomberg_, Apr 27 2015