A302631 Number of nX4 0..1 arrays with every element equal to 0, 1, 3 or 6 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.

5, 17, 14, 33, 101, 248, 657, 1841, 4892, 13020, 35447, 95226, 255042, 688238, 1852413, 4976015, 13395869, 36053423, 96953152, 260865015, 701948030, 1888295155, 5080237927, 13668712238, 36773414080, 98934258153, 266178278368

Offset: 1

Author

R. H. Hardin, Apr 10 2018

Keywords

• nonn

Comments

Column 4 of A302635.

Examples

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

Links

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

Crossrefs

Cf. A302635.

Formula

Empirical: a(n) = a(n-1) +2*a(n-2) +9*a(n-3) -12*a(n-5) -13*a(n-6) +2*a(n-7) +17*a(n-8) +13*a(n-9) -6*a(n-10) -16*a(n-11) -12*a(n-12) +6*a(n-13) +12*a(n-14) +5*a(n-15) -8*a(n-16) -10*a(n-17) -4*a(n-18) +3*a(n-19) +3*a(n-20) +a(n-21) for n>25