

A279128


Number of n X 2 0..1 arrays with no element equal to a strict majority of its horizontal and vertical neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.


3



1, 0, 9, 34, 87, 194, 400, 790, 1511, 2830, 5213, 9484, 17080, 30508, 54117, 95434, 167443, 292486, 508912, 882402, 1525219, 2628886, 4519577, 7751888, 13267384, 22662360, 38639553, 65769394, 111771663, 189671306, 321421456, 543987118
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OFFSET

1,3


COMMENTS



LINKS



FORMULA

Empirical: a(n) = 5*a(n1)  7*a(n2)  2*a(n3) + 10*a(n4)  2*a(n5)  5*a(n6) + a(n7) + a(n8) for n>9.
Empirical g.f.: x*(1  5*x + 16*x^2  9*x^3  30*x^4 + 17*x^5 + 22*x^6  x^7  9*x^8) / ((1  x)^2*(1  x  x^2)^3).  Colin Barker, Feb 26 2018


EXAMPLE

Some solutions for n=4:
..0..1. .0..1. .0..1. .0..1. .0..0. .0..0. .0..0. .0..1. .0..0. .0..0
..0..0. .1..1. .0..0. .0..1. .1..1. .1..0. .1..0. .1..0. .0..1. .1..0
..1..0. .0..1. .1..1. .1..1. .0..1. .0..1. .0..1. .1..0. .1..1. .1..0
..0..1. .0..1. .1..0. .0..0. .0..1. .1..1. .0..0. .0..0. .0..0. .0..1


CROSSREFS



KEYWORD

nonn


AUTHOR



STATUS

approved



