A334775 - OEIS

%I #9 Jan 11 2021 00:14:42

%S 1,3,24,339,7392,230217,9689934,529634931,36463272996,3086776079745,

%T 315108659732034,38170141911313467,5412679282489599840,

%U 888197438344278978537,166988574370806672234630,35659091146526471860555587,8583030980293328579564829948,2312892203852608268226402385617

%N Number of permutations of 2 indistinguishable copies of 1..n with exactly n local maxima.

%H Andrew Howroyd, <a href="/A334775/b334775.txt">Table of n, a(n) for n = 1..100</a>

%o (PARI) \\ PeaksBySig defined in A334774.

%o a(n)={ PeaksBySig(vector(n,i,2), [n-1])[1] }

%Y Main diagonal of A334774.

%K nonn

%O 1,2

%A _Andrew Howroyd_, May 11 2020