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 A246249 #10 Aug 26 2014 17:02:09 %S A246249 3052323,186723630,7683652710,260901740745,8002149813810, %T A246249 231524173618290,6486876741415365,178899784802719290, %U A246249 4910005699045578270,135118835430805648215,3748167756629344500390,105205858082972481706290,2996195115836815163207370 %N A246249 Number of permutations of [n] with exactly four occurrences of the consecutive step pattern up, down, down. %H A246249 Alois P. Heinz, <a href="/A246249/b246249.txt">Table of n, a(n) for n = 13..160</a> %F A246249 a(n) ~ c * (3*sqrt(3)/(2*Pi))^n * n! * n^4, where c = 0.000882722753946826148... = c0 * (c0-1)^4 / (3^4 * 4!), and c0 = (1 + exp(Pi/sqrt(3))) * sqrt(3) / (2*Pi). - _Vaclav Kotesovec_, Aug 26 2014 %Y A246249 Column k=4 of A242819. %K A246249 nonn %O A246249 13,1 %A A246249 _Alois P. Heinz_, Aug 20 2014