A152497 1/3 of the number of permutations of 2 indistinguishable copies of 1..n with exactly 5 local maxima.

0, 0, 0, 0, 2464, 744881, 104768981, 10276536243, 822955247485, 58200440129470, 3799361321633144, 235172542192199514, 14040457016024386686, 817688213483194898191, 46806533018464413823463, 2647280824791216788157413, 148469293685889945755890443, 8277727866556696292321356900

Offset: 1

Author

R. H. Hardin, Dec 06 2008

Keywords

• nonn

Links

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

Crossrefs

Cf. A334774.

Programs

PARI

\\ PeaksBySig defined in A334774.
a(n)={PeaksBySig(vector(n,i,2), [4])[1]/3} \\ Andrew Howroyd, May 12 2020

Formula

a(n) = A334774(n,5)/3. - Andrew Howroyd, May 12 2020

Extensions

Terms a(11) and beyond from Andrew Howroyd, May 12 2020