A279293 Number of permutations of [n] having exactly four (possibly overlapping) doubledescents.

1, 12, 316, 4961, 88482, 1456780, 24970807, 430069638, 7646066285, 139512608803, 2630205520242, 51191324887317, 1030225266241718, 21431850533761458, 460916811387051427, 10243049068068285706, 235127217600172319772, 5571780677576178939683

Offset

6,2

Links

Alois P. Heinz, Table of n, a(n) for n = 6..461

Formula

a(n) ~ c * 3^(3*n/2) * n^(n + 9/2) / (exp(n) * 2^n * Pi^n), where c = 0.000357063672536829943422824320618... . - Vaclav Kotesovec, Dec 22 2020

Crossrefs

Column k=4 of A162975.

Sequence in context: A323839 A163585 A341185 * A180790 A277072 A080325

Adjacent sequences: A279290 A279291 A279292 * A279294 A279295 A279296

Keyword

nonn

Author

Alois P. Heinz, Dec 09 2016

Status

approved