A159718 Number of permutations of 2 indistinguishable copies of 1..n arranged in a circle with exactly 4 local maxima.

0, 0, 0, 88, 33600, 3821760, 272509552, 15313310208, 750469872312, 33813251867920, 1443455210369040, 59454199364673024, 2389923754993613176, 94450458835284703536, 3687585353084799432720, 142691482885508987276800, 5484263653598164634676600, 209677462059979688650122960

Offset

1,4

Links

Andrew Howroyd, Table of n, a(n) for n = 1..200

Prog

(PARI) \\ CircPeaksBySig defined in A334778.
a(n) = {CircPeaksBySig(vector(n, i, 2), [4])[1]} \\ Andrew Howroyd, May 13 2020

Crossrefs

Column 4 of A334778.

Cf. A159716.

Sequence in context: A346926 A174499 A048919 * A157460 A267917 A093244

Adjacent sequences: A159715 A159716 A159717 * A159719 A159720 A159721

Keyword

nonn

Author

R. H. Hardin, Apr 20 2009

Extensions

Terms a(10) and beyond from Andrew Howroyd, May 13 2020

Status

approved