A159717 Number of permutations of 2 indistinguishable copies of 1..n arranged in a circle with exactly 3 local maxima.

0, 0, 6, 1192, 61830, 2150688, 62178928, 1629254640, 40346856234, 965510596600, 22606163844396, 521603874280248, 11911230805813846, 269907065756299440, 6079103449024019880, 136243494317831152480, 3040751938796332410018, 67621304208554979697224, 1499043510801269678080708

Offset

1,3

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), [3])[1]} \\ Andrew Howroyd, May 13 2020

Crossrefs

Column 3 of A334778.

Cf. A159716.

Sequence in context: A219165 A185537 A113159 * A160857 A160005 A172923

Adjacent sequences: A159714 A159715 A159716 * A159718 A159719 A159720

Keyword

nonn

Author

R. H. Hardin, Apr 20 2009

Extensions

Terms a(11) and beyond from Andrew Howroyd, May 13 2020

Status

approved