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 A216718 #17 Apr 16 2021 00:16:11 %S A216718 1,1,1,5,0,1,20,3,0,1,102,14,3,0,1,627,72,17,3,0,1,4461,468,87,20,3,0, %T A216718 1,36155,3453,582,103,23,3,0,1,328849,28782,4395,704,120,26,3,0,1, %U A216718 3317272,267831,37257,5435,834,138,29,3,0,1 %N A216718 Triangle read by rows: number of circular permutations of [1..n] with k progressions of rise 1, distance 1 and length 3 (n >= 3, k >= 0). %D A216718 Wayne M. Dymacek, Isaac Lambert and Kyle Parsons, Arithmetic Progressions in Permutations, http://math.ku.edu/~ilambert/CN.pdf, 2012. %e A216718 Triangle begins: %e A216718 1; %e A216718 1, 1; [this is row n=3] %e A216718 5, 0, 1; %e A216718 20, 3, 0, 1; %e A216718 102, 14, 3, 0, 1; %e A216718 627, 72, 17, 3, 0, 1; %e A216718 4461, 468, 87, 20, 3, 0, 1; %e A216718 36155, 3453, 582, 103, 23, 3, 0, 1; %e A216718 328849, 28782, 4395, 704, 120, 26, 3, 0, 1; %e A216718 3317272, 267831, 37257, 5435, 834, 138, 29, 3, 0, 1; %e A216718 ... %Y A216718 Cf. A216716, A174072, A165961, A180187. %K A216718 nonn,tabl %O A216718 2,4 %A A216718 _N. J. A. Sloane_, Sep 15 2012 %E A216718 a(2,0)=1 added by _N. J. A. Sloane_, Apr 16 2021