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Number of permutations of [n] with exactly four occurrences of the consecutive step pattern up, down, down.
2

%I #10 Aug 26 2014 17:02:09

%S 3052323,186723630,7683652710,260901740745,8002149813810,

%T 231524173618290,6486876741415365,178899784802719290,

%U 4910005699045578270,135118835430805648215,3748167756629344500390,105205858082972481706290,2996195115836815163207370

%N Number of permutations of [n] with exactly four occurrences of the consecutive step pattern up, down, down.

%H Alois P. Heinz, <a href="/A246249/b246249.txt">Table of n, a(n) for n = 13..160</a>

%F 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 Column k=4 of A242819.

%K nonn

%O 13,1

%A _Alois P. Heinz_, Aug 20 2014