A185536 1/6 the number of nX3 0..5 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors.

1, 110, 2990, 127570, 4403225, 167398110, 6079401960, 225574291125, 8285469213945, 305786452982260, 11260066599241195, 415073544779136460, 15292958690004125565, 563586551260018728505, 20767361004817999220125

Offset: 1

Author

R. H. Hardin Jan 30 2011

Keywords

• nonn

Comments

Column 3 of A185540

Examples

			Some solutions for 5X3 with a(1,1)=0
..0..0..0....0..0..0....0..0..3....0..0..3....0..0..0....0..0..0....0..3..3
..0..3..3....0..3..3....0..0..3....0..3..3....0..3..3....0..3..3....0..0..0
..4..0..0....4..1..3....3..3..1....1..0..0....0..2..2....2..2..3....5..2..0
..4..4..4....4..1..0....5..5..1....1..1..2....3..4..2....2..4..0....5..2..2
..5..5..4....0..0..0....4..4..4....5..5..2....3..4..4....2..4..0....5..5..5
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..200

Formula

Empirical: a(n)=22*a(n-1)+638*a(n-2)-2567*a(n-3)-29583*a(n-4)+27088*a(n-5)+209637*a(n-6)+620796*a(n-7)-1634411*a(n-8)-4083145*a(n-9)[phone]*a(n-10)-21827225*a(n-11)-42404829*a(n-12)-73933685*a(n-13)[phone]*a(n-14)-669370750*a(n-15)-1844490625*a(n-16)[phone]*a(n-17)[phone]*a(n-18)-14443984375*a(n-19)-34831953125*a(n-20)-42570312500*a(n-21)-47656250000*a(n-22)-78125000000*a(n-23)