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 A174077 #8 Apr 17 2021 08:34:16 %S A174077 1,1,2,0,24,80,504,3794,31616,290970,2973600,33311520,405781344, %T A174077 5342413414,75612197528,1144942063230,18471128518656,316309310084728, %U A174077 5730646943736936 %N A174077 Number of permutations of length n with no consecutive triples i,i+2,i+4 (mod n) or i,i-2,i-4 (mod n). %e A174077 As an example, (0,4,1,2,3) is counted by a(5), but (0,4,1,3,2) is not because it has the progression 4,1,3. %Y A174077 Cf. A165963, A174076, A174078, A174079. %K A174077 nonn,more %O A174077 0,3 %A A174077 _Isaac Lambert_, Mar 10 2010 %E A174077 Definition corrected by _Isaac Lambert_, Mar 15 2010 %E A174077 a(0)-a(4) and a(10)-a(18) from _Alois P. Heinz_, Apr 15 2021