

A197274


Number of n X 2 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 2,0,1,1,1 for x=0,1,2,3,4.


1



3, 9, 14, 29, 67, 134, 275, 583, 1210, 2511, 5245, 10926, 22745, 47405, 98774, 205765, 428731, 893294, 1861163, 3877815, 8079642, 16834247, 35074949, 73080470, 152266769, 317255517, 661018310, 1377265789, 2869604691, 5978971062
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OFFSET

1,1


COMMENTS

Every 0 is next to 0 2's, every 1 is next to 1 0's, every 2 is next to 2 1's, every 3 is next to 3 1's, every 4 is next to 4 1's.


LINKS



FORMULA

Empirical: a(n) = 2*a(n1) +2*a(n3) 2*a(n4) 2*a(n5) a(n6) 2*a(n7).
Empirical g.f.: (1 + x)^2*(3  3*x  x^2  2*x^4) / (1  2*x  2*x^3 + 2*x^4 + 2*x^5 + x^6 + 2*x^7).  Colin Barker, May 11 2018


EXAMPLE

Some solutions for n=4:
..2..1....0..0....0..1....0..1....2..1....0..0....2..1....1..0....1..0....0..1
..1..0....0..0....1..1....0..1....1..0....1..1....1..0....3..1....1..0....1..3
..1..0....0..0....1..0....0..1....1..0....1..1....1..1....1..1....1..0....1..1
..2..1....0..0....2..1....1..2....1..0....0..0....0..1....0..0....1..0....0..0


CROSSREFS



KEYWORD

nonn


AUTHOR



STATUS

approved



