A302637 Number of 4 X n 0..1 arrays with every element equal to 0, 1, 3 or 6 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.

8, 10, 19, 33, 65, 149, 304, 643, 1343, 2880, 6038, 12805, 27015, 57283, 120917, 255898, 540904, 1144495, 2419416, 5117330, 10820901, 22886110, 48394996, 102347752, 216437366, 457724270, 967964774, 2047035882, 4328987213

Offset: 1

Author

R. H. Hardin, Apr 10 2018

Keywords

• nonn

Comments

Row 4 of A302635.

Examples

			Some solutions for n=5
..0..1..0..1..0. .0..1..0..0..1. .0..1..1..0..1. .0..0..1..1..0
..0..1..0..1..1. .0..1..0..1..0. .1..0..1..0..0. .0..1..0..1..0
..0..0..0..1..0. .0..1..0..1..0. .1..0..1..0..1. .0..1..0..1..0
..0..1..0..1..0. .1..0..0..1..0. .1..0..1..0..1. .0..1..1..0..0
		

Links

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

Crossrefs

Cf. A302635.

Formula

Empirical: a(n) = a(n-1) +a(n-2) +2*a(n-3) +8*a(n-4) -6*a(n-5) -6*a(n-6) -13*a(n-7) -22*a(n-8) +7*a(n-9) +11*a(n-10) +28*a(n-11) +28*a(n-12) +2*a(n-13) -9*a(n-14) -27*a(n-15) -17*a(n-16) -2*a(n-17) +4*a(n-18) +10*a(n-19) +4*a(n-20) -2*a(n-21) -a(n-22) for n > 23.