A264471 Number of (n+1)X(3+1) arrays of permutations of 0..n*4+3 with each element having directed index change 0,1 1,0 2,1 or -1,-1.

0, 4, 6, 16, 49, 124, 384, 1041, 2868, 8189, 22760, 63910, 179095, 500979, 1405340, 3935526, 11024880, 30892270, 86537090, 242454683, 679254490, 1902958308, 5331384633, 14936238820, 41845207329, 117233159460, 328438385380

Offset: 1

Author

R. H. Hardin, Nov 14 2015

Keywords

• nonn

Comments

Column 3 of A264476.

Examples

			Some solutions for n=4
..5..0..1..2....5..6..7..2....5..0..7..2....5..6..7..2....5..6..7..2
..9..4.11..3....0..4.11..3....9..1.11..3....0..1.11..3....9..4.11..3
.13.14.15..7...13..8..1.10...13.14.15.10...13..8.15.10...13..0..1.10
..8.18.19..6...17.18.19.14....8..4.19..6...17..4.19.14....8.18.19.14
.12.16.17.10...12.16..9.15...12.16.17.18...12.16..9.18...12.16.17.15
		

Links

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

Crossrefs

Cf. A264476.

Formula

Empirical: a(n) = 2*a(n-1) +a(n-2) +6*a(n-3) -6*a(n-4) +6*a(n-5) -27*a(n-6) +5*a(n-7) -9*a(n-8) +33*a(n-9) -4*a(n-10) +7*a(n-11) -12*a(n-12) +a(n-13) -a(n-14) +a(n-15)