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A177557 Number of permutations of 2 copies of 1..n avoiding adjacent step pattern up, down, up. 0

%I

%S 1,5,55,1062,31147,1313796,75373533,5661748406,539467979009,

%T 63618193828712,9098617148960622,1551945898935373561,

%U 311275951583298747596,72535753321856685723563

%N Number of permutations of 2 copies of 1..n avoiding adjacent step pattern up, down, up.

%K nonn

%O 1,2

%A _R. H. Hardin_, May 10 2010

%E a(11)-a(14) from _Alois P. Heinz_, Nov 02 2013

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Last modified October 20 12:43 EDT 2021. Contains 348108 sequences. (Running on oeis4.)