A226436 Number of permutations of 1..n with fewer than 3 interior elements having values lying between the values of their neighbors

1, 2, 6, 24, 118, 658, 4078, 27724, 205134, 1641534, 14132390, 130299584, 1281352790, 13391026730, 148237230942, 1733059331604, 21341010960286, 276120222880246, 3745333514843734, 53149568086851784, 787599172764342822

Offset

1,2

Comments

Column 3 of A226441

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Example

Some solutions for n=9
..6....4....3....9....7....7....9....5....8....8....1....8....8....7....6....2
..1....2....2....2....3....4....3....3....1....4....4....3....4....1....4....1
..3....8....8....1....2....8....4....9....9....3....3....9....2....2....8....7
..9....3....7....6....8....3....2....1....4....7....5....5....9....6....5....9
..5....7....5....5....5....5....5....8....6....6....2....7....1....3....9....3
..2....9....6....3....1....9....7....2....7....2....8....4....5....5....2....6
..8....1....4....7....6....1....6....7....3....9....9....6....3....8....3....4
..4....5....9....4....4....6....1....4....5....1....7....2....6....4....1....5
..7....6....1....8....9....2....8....6....2....5....6....1....7....9....7....8

Crossrefs

Sequence in context: A319027 A228397 A164871 * A224318 A079106 A247472

Adjacent sequences: A226433 A226434 A226435 * A226437 A226438 A226439

Keyword

nonn

Author

R. H. Hardin Jun 06 2013

Status

approved