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A302624
Number of 3Xn 0..1 arrays with every element equal to 0, 1, 2 or 6 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.
1
4, 25, 25, 45, 79, 146, 286, 563, 1114, 2222, 4435, 8858, 17710, 35411, 70810, 141614, 283219, 566426, 1132846, 2265683, 4531354, 9062702, 18125395, 36250778, 72501550, 145003091, 290006170, 580012334, 1160024659, 2320049306, 4640098606
OFFSET
1,1
COMMENTS
Row 3 of A302623.
LINKS
FORMULA
Empirical: a(n) = 2*a(n-1) +a(n-3) -2*a(n-4) for n>8
EXAMPLE
Some solutions for n=5
..0..1..0..1..1. .0..0..1..0..1. .0..1..1..0..1. .0..1..0..1..1
..0..1..0..1..0. .1..0..0..0..1. .0..0..1..0..1. .1..0..1..0..0
..1..1..0..1..1. .1..0..1..0..1. .1..0..1..0..0. .1..0..1..0..1
CROSSREFS
Cf. A302623.
Sequence in context: A114392 A281471 A107734 * A238515 A043067 A289273
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 10 2018
STATUS
approved