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R. H. Hardin, <a href="/A297540/b297540.txt">Table of n, a(n) for n = 1..210</a>

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Number of nX4 0..1 arrays with every 1 horizontally, diagonally or antidiagonally adjacent to 2 or 3 neighboring 1s.

1, 24, 93, 275, 2205, 13248, 67215, 401415, 2403621, 13717554, 79734011, 467605069, 2718919839, 15817878296, 92253538261, 537481451021, 3130277448285, 18239061232932, 106267286686423, 619075960613237, 3606738104606245

1,2

Column 4 of A297544.

Empirical: a(n) = 4*a(n-1) +6*a(n-2) +48*a(n-3) -58*a(n-4) -327*a(n-5) -368*a(n-6) +322*a(n-7) +1099*a(n-8) +949*a(n-9) +1014*a(n-10) +648*a(n-11) +1037*a(n-12) +38*a(n-13) -301*a(n-14) -141*a(n-15) -197*a(n-16) -151*a(n-17) -27*a(n-18) +33*a(n-19) +32*a(n-20) +3*a(n-21) -2*a(n-22)

Some solutions for n=5

..0..1..1..0. .1..1..0..0. .0..0..1..1. .0..0..1..0. .0..1..0..0

..0..0..1..1. .1..1..0..0. .0..1..1..0. .0..1..1..1. .1..0..1..0

..0..1..0..0. .1..1..0..0. .1..0..0..0. .1..0..0..1. .0..1..0..0

..1..1..0..0. .1..1..0..0. .0..1..1..0. .0..1..1..0. .0..1..1..0

..1..1..0..0. .0..0..0..0. .1..1..0..0. .1..1..0..0. .0..1..1..0

Cf. A297544.

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R. H. Hardin, Dec 31 2017

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