A279292 Number of permutations of [n] having exactly three (possibly overlapping) doubledescents.

1, 10, 167, 2064, 28143, 374166, 5227491, 75105984, 1127851278, 17625022976, 287569327286, 4891520843344, 86749331150517, 1602239541108282, 30795187124606301, 615261376037422992, 12764913390565572333, 274721686459213597782, 6126847681304067647287

Offset

5,2

Links

Alois P. Heinz, Table of n, a(n) for n = 5..462

Formula

a(n) ~ c * 3^(3*n/2) * n^(n+7/2) / (exp(n) * 2^n * Pi^n), where c = 0.0065517603957816327489026... . - Vaclav Kotesovec, Dec 11 2016

Crossrefs

Column k=3 of A162975.

Sequence in context: A112650 A006295 A006297 * A099711 A203532 A325911

Adjacent sequences: A279289 A279290 A279291 * A279293 A279294 A279295

Keyword

nonn

Author

Alois P. Heinz, Dec 09 2016

Status

approved