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A302165
Number of 3Xn 0..1 arrays with every element equal to 0, 1 or 3 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.
1
4, 6, 7, 12, 20, 34, 56, 94, 156, 262, 436, 730, 1216, 2034, 3392, 5670, 9460, 15806, 26380, 44066, 73560, 122858, 205112, 342542, 571916, 955062, 1594660, 2662890, 4446320, 7424674, 12397424, 20701558, 34566948, 57720430, 96380668, 160937266
OFFSET
1,1
COMMENTS
Row 3 of A302163.
LINKS
FORMULA
Empirical: a(n) = a(n-1) +a(n-2) -a(n-3) +2*a(n-4) for n>6
EXAMPLE
Some solutions for n=5
..0..0..1..0..1. .0..0..1..1..0. .0..1..0..1..0. .0..1..0..1..0
..0..1..0..0..1. .0..1..0..1..0. .0..1..0..1..1. .1..1..0..1..1
..0..1..0..1..0. .0..1..0..1..0. .0..1..0..1..0. .0..1..0..1..0
CROSSREFS
Cf. A302163.
Sequence in context: A310656 A102136 A102142 * A102144 A102138 A002151
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 02 2018
STATUS
approved