A198522 - OEIS

%I #8 Apr 21 2021 11:02:13

%S 2,15,193,3660,81844,1948672,47436498,1163606279,28617909415,

%T 704465305625,17346617064022,427184684002131,10520398796919219,

%U 259092051772297458,6380839372392481249,157145577058895542027

%N Number of n X 2 0..4 arrays with values 0..4 introduced in row major order and each element equal to no more than two horizontal and vertical neighbors.

%C Column 2 of A198528.

%H R. H. Hardin, <a href="/A198522/b198522.txt">Table of n, a(n) for n = 1..200</a>

%F Empirical: a(n) = 35*a(n-1) -267*a(n-2) +246*a(n-3) +924*a(n-4) +710*a(n-5) -1736*a(n-6) -1860*a(n-7) +72*a(n-8) +1984*a(n-9) +720*a(n-10) -320*a(n-11) -512*a(n-12) for n > 14.

%e Some solutions for n=4

%e ..0..0....0..1....0..0....0..1....0..1....0..1....0..1....0..0....0..1....0..0

%e ..0..1....2..0....1..0....2..3....2..0....2..0....0..2....0..1....2..3....1..2

%e ..2..3....2..2....2..3....4..2....1..0....0..2....1..3....1..0....1..2....1..3

%e ..2..2....3..1....0..1....0..3....2..1....2..3....0..0....0..0....1..0....1..2

%Y Cf. A198528.

%K nonn

%O 1,1

%A _R. H. Hardin_ Oct 26 2011