A189601 Number of permutations of 1..n with displacements restricted to {-7,-6,-5,-4,-3,-1,0,2}

1, 1, 2, 4, 10, 23, 51, 117, 250, 524, 1123, 2428, 5274, 11493, 24927, 54025, 117003, 253155, 548139, 1187354, 2572374, 5573514, 12074638, 26156163, 56658896, 122731402, 265858041, 575909407, 1247556710, 2702508126, 5854265152

Offset

1,3

Links

R. H. Hardin, Table of n, a(n) for n = 1..200

Formula

Empirical: a(n) = a(n-1) +a(n-2) +a(n-3) +a(n-4) +4*a(n-5) +4*a(n-6) +7*a(n-7) +12*a(n-8) +11*a(n-9) -15*a(n-10) +a(n-11) -7*a(n-12) -14*a(n-13) +12*a(n-14) -12*a(n-15) -13*a(n-16) -5*a(n-17) -3*a(n-18) -2*a(n-19) -2*a(n-21) +2*a(n-22) +2*a(n-23) +5*a(n-24) +5*a(n-25) +a(n-26) +3*a(n-27) +2*a(n-28) +a(n-29) -a(n-30) +a(n-32) -a(n-33) -a(n-34)

Example

Some solutions for n=10
..1....2....1....5....1....1....1....2....5....1....1....2....1....2....2....1
..5....3....2....7....9....2....5....3....3....3....2....7....9....3....5....9
..4....1....6....1....4....4....4....1....1....6....3....1....3....1....1....3
..2...10...10....2....2....8....2....4....2....2....4....5....2...10....4....2
..3....9....3....3....3....3....3....5...10....5....9....3...10....5....3....5
..7....4....4....4...10....7....6....6....4....4...10....4....4....4....6....4
..8....5....5...10....5....5....7....8....7....7....5...10....5....7....8...10
..6....6....9....6....6....6....8....9....6....9....6....6....6....6....9....6
..9....7....7....9....7....9....9....7....9...10....7....9....7....9....7....7
.10....8....8....8....8...10...10...10....8....8....8....8....8....8...10....8

Crossrefs

Sequence in context: A018111 A189594 A094987 * A210460 A329669 A191693

Adjacent sequences: A189598 A189599 A189600 * A189602 A189603 A189604

Keyword

nonn

Author

R. H. Hardin Apr 24 2011

Status

approved