A152498 1/3 of the number of permutations of 2 indistinguishable copies of 1..n with exactly 6 local maxima.

0, 0, 0, 0, 0, 76739, 42734373, 10478384089, 1717626773713, 222419564005134, 24781841211038024, 2496351029911357950, 234485896532293552830, 20959967704130971672341, 1807748255927878129526087, 151901517836714997413430591, 12521620421275657891377640951

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), [5])[1]/3}

Formula

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

Extensions

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