A159718 - OEIS

%I #6 May 13 2020 13:01:04

%S 0,0,0,88,33600,3821760,272509552,15313310208,750469872312,

%T 33813251867920,1443455210369040,59454199364673024,

%U 2389923754993613176,94450458835284703536,3687585353084799432720,142691482885508987276800,5484263653598164634676600,209677462059979688650122960

%N Number of permutations of 2 indistinguishable copies of 1..n arranged in a circle with exactly 4 local maxima.

%H Andrew Howroyd, <a href="/A159718/b159718.txt">Table of n, a(n) for n = 1..200</a>

%o (PARI) \\ CircPeaksBySig defined in A334778.

%o a(n) = {CircPeaksBySig(vector(n, i, 2), [4])[1]} \\ _Andrew Howroyd_, May 13 2020

%Y Column 4 of A334778.

%Y Cf. A159716.

%K nonn

%O 1,4

%A _R. H. Hardin_, Apr 20 2009

%E Terms a(10) and beyond from _Andrew Howroyd_, May 13 2020