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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. 1
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Column 3 of A304926.
LINKS
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
KEYWORD
nonn
AUTHOR
R. H. Hardin, May 21 2018
STATUS
approved

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Last modified July 17 09:00 EDT 2024. Contains 374363 sequences. (Running on oeis4.)