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 A174087 #12 Jan 19 2022 08:16:06 %S A174087 4,0,12,0,96,1296,1520,23540,101472,686724 %N A174087 Number of circular permutations with no arithmetic progressions i, ..., i+r, ..., i+2r (mod n) of any equal spacings d. %C A174087 Circular permutations are permutations whose indices are from the ring of integers modulo n. Here we count both the sequence 1,2,3 (r=1) as a progression in 1,2,3,0,4,5, (note d=1) and in 1,0,2,4,3,5 (here, d=2). %H A174087 Peter Hegarty, <a href="https://doi.org/10.37236/1792">Permutations avoiding arithmetic patterns</a>, The Electronic Journal of Combinatorics, 11 (2004), #R39 (includes this sequence times n). %e A174087 a(4) has the same value as A078628(4) since the only possible distance is 1. %Y A174087 Cf. A078628, A174084, A174085, A174086. %K A174087 nonn,more %O A174087 4,1 %A A174087 _Isaac Lambert_, Apr 20 2010