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A283516
Number of nX2 0..1 arrays with no 1 equal to more than three of its horizontal, vertical and antidiagonal neighbors, with the exception of exactly two elements.
1
0, 0, 1, 5, 28, 145, 703, 3288, 14980, 66958, 294864, 1283142, 5529698, 23637592, 100350059, 423511851, 1778210188, 7432635711, 30943479193, 128365649488, 530810149910, 2188638842860, 9000532494016, 36925016172060, 151153394192532
OFFSET
1,4
COMMENTS
Column 2 of A283522.
LINKS
FORMULA
Empirical: a(n) = 9*a(n-1) -18*a(n-2) -24*a(n-3) +39*a(n-4) +75*a(n-5) +69*a(n-6) +93*a(n-7) +99*a(n-8) +67*a(n-9) +45*a(n-10) +33*a(n-11) +16*a(n-12) +6*a(n-13) +3*a(n-14) +a(n-15)
EXAMPLE
All solutions for n=4
..0..0. .0..1. .1..1. .1..0. .1..1
..1..1. .1..1. .1..1. .1..1. .1..1
..1..1. .1..1. .1..1. .1..1. .1..1
..1..1. .1..0. .0..1. .1..1. .0..0
CROSSREFS
Cf. A283522.
Sequence in context: A037682 A271686 A272288 * A126699 A267828 A164537
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 09 2017
STATUS
approved