A304921 Number of nX3 0..1 arrays with every element unequal to 0, 1, 2, 5 or 7 king-move adjacent elements, with upper left element zero.

4, 5, 15, 31, 73, 191, 466, 1125, 2762, 6805, 16682, 40883, 100333, 246242, 604110, 1482121, 3636605, 8922832, 21892633, 53715047, 131794387, 323367960, 793407563, 1946686405, 4776346628, 11719135709, 28753802800, 70549676372, 173099084553

Offset

1,1

Comments

Column 3 of A304926.

Links

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

Formula

Empirical: a(n) = a(n-1) +2*a(n-2) +4*a(n-3) +2*a(n-4) -2*a(n-5) -7*a(n-6) -6*a(n-7) for n>9

Example

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

Crossrefs

Cf. A304926.

Sequence in context: A184244 A006491 A321174 * A357927 A051721 A050226

Adjacent sequences: A304918 A304919 A304920 * A304922 A304923 A304924

Keyword

nonn

Author

R. H. Hardin, May 21 2018

Status

approved