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 A134292 #13 Feb 16 2025 08:33:06 %S A134292 1,2,1,2,3,4,1,4,3,2,5,6,1,2,3,8,5,6,7,4,1,2,3,4,7,6,5,8,9,10,1,2,3,4, %T A134292 7,6,5,12,11,8,9,10,1,2,3,4,7,6,13,10,9,14,5,8,11,12,1,2,3,4,7,6,5,12, %U A134292 11,8,9,14,15,16,13,10,1,2,3,4,7,6,5,8,9,10,13,16,15,14,17,12,11,18,1,2,3 %N A134292 Triangle in which row n is the lexicographically earliest solution to the prime circle problem for 2n. %C A134292 In the prime circle problem we seek to arrange the numbers 1 to 2n around a circle so that the sum of each pair of adjacent numbers is prime. To display the solution, we unroll the circle starting at 1. %D A134292 R. K. Guy, Unsolved Problems Number Theory, Section C1. %H A134292 T. D. Noe, <a href="/A134292/b134292.txt">Rows n=1..50 of triangle, flattened</a> %H A134292 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PrimeCircle.html">Prime Circle</a> %e A134292 Triangle begins: %e A134292 1, 2; %e A134292 1, 2, 3, 4; %e A134292 1, 4, 3, 2, 5, 6; %e A134292 1, 2, 3, 8, 5, 6, 7, 4; %e A134292 ... %Y A134292 Cf. A051252 (number of solutions for each n), A051237 (prime pyramid). %K A134292 nice,nonn,look,tabf %O A134292 1,2 %A A134292 _T. D. Noe_, Oct 16 2007