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A318062 Number of nX2 0..1 arrays with every element unequal to 1, 2, 3 or 4 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero. 1
1, 5, 18, 67, 249, 925, 3437, 12770, 47447, 176289, 655001, 2433653, 9042226, 33596347, 124827065, 463794357, 1723225693, 6402636738, 23788965871, 88387787777, 328404398513, 1220184956261, 4533591310674, 16844536614515 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Column 2 of A318068.
LINKS
FORMULA
Empirical: a(n) = 3*a(n-1) +3*a(n-2) -a(n-3) -a(n-4)
EXAMPLE
Some solutions for n=5
..0..1. .0..0. .0..1. .0..0. .0..0. .0..0. .0..0. .0..1. .0..1. .0..1
..1..1. .1..0. .0..0. .1..1. .1..1. .1..0. .1..0. .1..0. .0..0. .0..1
..0..1. .0..0. .1..0. .0..1. .1..0. .1..1. .0..1. .0..1. .1..0. .0..0
..0..0. .0..1. .0..0. .1..1. .1..0. .0..0. .1..1. .0..1. .1..1. .1..1
..1..1. .0..0. .1..1. .0..1. .1..0. .1..1. .0..1. .1..0. .0..0. .1..0
CROSSREFS
Cf. A318068.
Sequence in context: A225015 A371871 A166677 * A158879 A322497 A279488
KEYWORD
nonn
AUTHOR
R. H. Hardin, Aug 15 2018
STATUS
approved

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Last modified April 24 06:07 EDT 2024. Contains 371918 sequences. (Running on oeis4.)