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 A081157 #8 Jan 11 2024 09:18:23 %S A081157 0,0,0,0,0,2,8,20,60,148,402,986,2474,5918,14496,34708,84282,202664, %T A081157 492048 %N A081157 Number of even cycles in range [A014137(n-1)..A014138(n-1)] of permutation A057505/A057506, with no fixed points of either A057163 or A057164. %Y A081157 Cf. A014137, A014138, A057505, A057506, A057163, A057164 %Y A081157 Bisections: A081158, A081159. Cf. A081150, A081160, A081162. %K A081157 nonn,more %O A081157 0,6 %A A081157 _Wouter Meeussen_ and _Antti Karttunen_, Mar 10 2003