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

1,5

Links

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

Formula

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

Prog

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

Crossrefs

Cf. A334774.

Sequence in context: A020431 A236707 A304554 * A365022 A329240 A182381

Adjacent sequences: A152494 A152495 A152496 * A152498 A152499 A152500

Keyword

nonn

Author

R. H. Hardin, Dec 06 2008

Extensions

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

Status

approved