A303620 Number of nX4 0..1 arrays with every element equal to 0, 2, 3, 4, 5 or 6 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.

1, 20, 68, 325, 1870, 10741, 62207, 363485, 2135551, 12586013, 74323727, 439462339, 2600501501, 15395919313, 91177465195, 540072985865, 3199404347759, 18954749501705, 112301887289875, 665378205627245, 3942374534440139

Offset: 1

Author

R. H. Hardin, Apr 27 2018

Keywords

• nonn

Comments

Column 4 of A303624.

Examples

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

Links

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

Crossrefs

Cf. A303624.

Formula

Empirical: a(n) = 9*a(n-1) -19*a(n-2) +19*a(n-3) -91*a(n-4) +33*a(n-5) -46*a(n-6) +295*a(n-7) +125*a(n-8) +527*a(n-9) -181*a(n-10) -44*a(n-11) -219*a(n-12) -360*a(n-13) +52*a(n-14) -131*a(n-15) -93*a(n-16) +23*a(n-17) +10*a(n-18) +70*a(n-19) +14*a(n-20) -16*a(n-21) +24*a(n-22) for n>24