A334775 - OEIS

A334775

Number of permutations of 2 indistinguishable copies of 1..n with exactly n local maxima.

1, 3, 24, 339, 7392, 230217, 9689934, 529634931, 36463272996, 3086776079745, 315108659732034, 38170141911313467, 5412679282489599840, 888197438344278978537, 166988574370806672234630, 35659091146526471860555587, 8583030980293328579564829948, 2312892203852608268226402385617

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OFFSET

1,2

LINKS

Andrew Howroyd, Table of n, a(n) for n = 1..100

FORMULA

a(n) ~ 2^(3*n + 5) * n^(2*n + 3/2) / (exp(2*n + 1/2) * Pi^(2*n + 3/2)). - Vaclav Kotesovec, Feb 10 2026

PROG

(PARI) \\ PeaksBySig defined in A334774.

a(n)={ PeaksBySig(vector(n, i, 2), [n-1])[1] }

CROSSREFS

Main diagonal of A334774.