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

1,2

Comments

Column 4 of A303624.

Links

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

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

Example

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

Crossrefs

Cf. A303624.

Sequence in context: A330931 A158444 A235281 * A221521 A145191 A044158

Adjacent sequences: A303617 A303618 A303619 * A303621 A303622 A303623

Keyword

nonn

Author

R. H. Hardin, Apr 27 2018

Status

approved