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A297695
Number of 2Xn 0..1 arrays with every 1 horizontally, diagonally or antidiagonally adjacent to 0, 2 or 4 neighboring 1s.
1
4, 8, 26, 60, 176, 436, 1216, 3120, 8488, 22160, 59552, 156816, 418880, 1107712, 2950048, 7817664, 20789248, 55148864, 146548736, 388957440, 1033216640, 2742970624, 7285063168, 19342708992, 51367846912, 136396150784, 362207435264
OFFSET
1,1
COMMENTS
Row 2 of A297694.
LINKS
FORMULA
Empirical: a(n) = 2*a(n-1) +4*a(n-2) -6*a(n-3)
EXAMPLE
Some solutions for n=7
..1..0..0..0..0..1..0. .1..0..1..0..0..0..0. .1..0..0..1..0..1..1
..1..0..1..0..0..1..0. .1..0..0..0..1..0..0. .1..0..1..1..1..1..0
CROSSREFS
Cf. A297694.
Sequence in context: A227644 A074188 A126733 * A333894 A218079 A012982
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 03 2018
STATUS
approved