A264545 Number of (n+1)X(3+1) arrays of permutations of 0..n*4+3 with each element having directed index change -1,1 -1,2 1,0 or 0,-1.

1, 6, 16, 45, 133, 400, 1204, 3561, 10554, 31493, 93784, 278862, 829809, 2469737, 7349616, 21870896, 65083321, 193678264, 576359005, 1715146434, 5103989104, 15188659597, 45198999981, 134504868528, 400264674436, 1191122820729

Offset: 1

Author

R. H. Hardin, Nov 17 2015

Keywords

• nonn

Comments

Column 3 of A264550.

Examples

			Some solutions for n=4
..1..2..5..6....1..2..3..5....1..2..3..5....1..4..3..6....1..2..3..5
..0..8..9..3....0..6..7.10....0..8..9.10....0..8..2.10....0..6..7..9
..4.10.12..7....4.12.11.14....4.12..6..7....9..5.12..7....4.10.11.14
.13.14.16.11....8..9.16.18...13.14.16.11...13.14.16.11....8.16.17.18
.17.18.19.15...17.13.19.15...17.18.19.15...17.18.19.15...12.13.19.15
		

Links

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

Crossrefs

Cf. A264550.

Formula

Empirical: a(n) = 2*a(n-1) +10*a(n-3) -4*a(n-4) +8*a(n-5) -25*a(n-6) -4*a(n-8) +33*a(n-9) +4*a(n-10) -4*a(n-11) -10*a(n-12) -2*a(n-13) +a(n-15)