A264630 Number of (3+1)X(n+1) arrays of permutations of 0..n*4+3 with each element having directed index change -2,0 -1,0 0,-1 or 1,1.

2, 4, 13, 40, 125, 393, 1200, 3759, 11572, 36004, 111380, 345489, 1070564, 3318409, 10285305, 31878944, 98808901, 306255436, 949236490, 2942139012, 9119124333, 28264569620, 87605626309, 271532263929, 841610129904, 2608557687707

Offset: 1

Author

R. H. Hardin, Nov 19 2015

Keywords

• nonn

Comments

Row 3 of A264628.

Examples

			Some solutions for n=4
..1.11..7..4..9....1..2..7..4..9....5.11..3..4..9....1.11..3..4..9
..6..0..8..2..3...10..0.12.18..3....6..0..1..2.14...10..0..8..2.14
.15..5.17.14.19...15..5..6.14..8...15.12.17..7..8...15..5..6..7.19
.16.10.18.12.13...16.17.11.19.13...16.10.18.19.13...16.17.18.12.13
		

Links

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

Crossrefs

Cf. A264628.

Formula

Empirical: a(n) = 6*a(n-2) +10*a(n-3) +4*a(n-4) -2*a(n-5) -a(n-6) +4*a(n-7) +18*a(n-8) +25*a(n-9) -8*a(n-10) -6*a(n-11) -10*a(n-12) +a(n-15)