|
%I #7 Jan 01 2024 19:25:32
%S 1,4,16,50,184,810,3502,14751,63204,274824,1195748,5201911,22685592,
%T 99123373,433452835,1896510229,8302931200,36367291798,159341158550,
%U 698313973844,3060976848490,13419502926856,58838771883237
%N Number of n X 2 0..3 arrays with every nonzero element less than or equal to at least two horizontal and vertical neighbors.
%C Column 2 of A203846.
%H R. H. Hardin, <a href="/A203840/b203840.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 10*a(n-1) -39*a(n-2) +104*a(n-3) -251*a(n-4) +391*a(n-5) -483*a(n-6) +687*a(n-7) -378*a(n-8) +503*a(n-9) -247*a(n-10) -66*a(n-11) -292*a(n-12) -300*a(n-13) -217*a(n-14) -153*a(n-15) -70*a(n-16) -27*a(n-17) -8*a(n-18) -a(n-19).
%e Some solutions for n=4
%e ..3..3....1..1....2..2....3..3....3..3....1..1....1..1....2..2....0..0....0..0
%e ..3..3....2..2....2..2....3..3....3..3....1..1....3..3....3..3....2..2....0..0
%e ..1..1....2..2....0..0....1..1....1..1....2..2....3..3....3..3....2..2....0..0
%e ..0..0....0..0....0..0....0..0....0..0....2..2....0..0....3..3....0..0....0..0
%Y Cf. A203846.
%K nonn
%O 1,2
%A _R. H. Hardin_, Jan 06 2012
| 