A334779 Number of permutations of 2 indistinguishable copies of 1..n arranged in a circle with exactly n local maxima.

1, 1, 2, 6, 88, 1480, 40272, 1476944, 71865728, 4454840448, 343059301120, 32120367997696, 3593423957597184, 473387964389590016, 72533147097036867584, 12789470502905585018880, 2571336187676016073080832, 584713932920281483718459392, 149314675071137196105777217536

Offset

0,3

Links

Andrew Howroyd, Table of n, a(n) for n = 0..100

Prog

(PARI) \\ CircPeaksBySig defined in A334778.
a(n) = {if(n==0, 1, CircPeaksBySig(vector(n, i, 2), [n])[1])} \\ Andrew Howroyd, May 13 2020

Crossrefs

Main diagonal of A334778.

Sequence in context: A268534 A055702 A364794 * A305598 A179214 A128265

Adjacent sequences: A334776 A334777 A334778 * A334780 A334781 A334782

Keyword

nonn

Author

Andrew Howroyd, May 13 2020

Status

approved