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 A179957 #12 Feb 12 2025 15:29:38 %S A179957 1,1,0,0,0,0,0,0,2,72,1496,25384,399848,6231544,99133496,1634227958, %T A179957 28120703888,506599465896,9562489659952,189055933191880, %U A179957 3911226769004280,84567966329357056 %N A179957 Number of permutations of 1..n such that |p(i)-p(i-1)|>= 4 for i>1. %K A179957 nonn %O A179957 0,9 %A A179957 _R. H. Hardin_, Aug 03 2010 %E A179957 a(0), a(19)-a(20) from _Alois P. Heinz_, Oct 27 2014 %E A179957 a(21) from _Alois P. Heinz_, Feb 10 2025