A263960 Number of (n+1) X (2+1) arrays of permutations of 0..n*3+2 with each element having index change (+-,+-) 0,0 1,1 or 1,2.

20, 141, 1685, 16856, 183229, 1926873, 20563180, 218090365, 2319277277, 24635857104, 261817809677, 2781874723553, 29560794485380, 314106805739181, 3337690330530853, 35465944138655752, 376858567864983197

Offset

1,1

Links

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

Formula

Empirical: a(n) = 8*a(n-1) + 40*a(n-2) - 119*a(n-3) - 124*a(n-4) + 240*a(n-5).

Empirical g.f.: x*(20 - 19*x - 243*x^2 + 116*x^3 + 240*x^4) / (1 - 8*x - 40*x^2 + 119*x^3 + 124*x^4 - 240*x^5). - Colin Barker, Jan 03 2019

Example

Some solutions for n=4:
..5..1..3....5..1..3....5..1..4....4..5..3....0..3..4....5..1..4....0..3..2
..2..0..6....2..0..7....3..2..0....1..2..0....1..2..6....8..2..0....8..6..1
..4..7.10...10..9..4...11..7.10...11..9.10...11..5..8...10.11..3...10..5..4
..9..8.11....8..6.12....9..8..6....7..8..6....9.14..7...14..6..7...13.12..7
.12.13.14...11.13.14...12.13.14...12.13.14...12.13.10...12.13..9...11..9.14

Crossrefs

Column 2 of A263964.

Sequence in context: A253003 A293932 A071816 * A190067 A238021 A183959

Adjacent sequences: A263957 A263958 A263959 * A263961 A263962 A263963

Keyword

nonn

Author

R. H. Hardin, Oct 30 2015

Status

approved