A240193 Number of 3 X n 0..3 arrays with no element equal to zero plus the sum of elements to its left or one plus the sum of the elements above it or three plus the sum of the elements diagonally to its northwest, modulo 4.

3, 12, 37, 129, 478, 1908, 7868, 32888, 138292, 583040, 2461028, 10393720, 43907108, 185502448, 783769556, 3311604104, 13992449972, 59122342816, 249810507844, 1055529401752, 4459952527044, 18844744947024, 79625166220340

Offset: 1

Author

R. H. Hardin, Apr 02 2014

Keywords

• nonn

Examples

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

Links

• R. H. Hardin, Table of n, a(n) for n = 1..210

Crossrefs

Row 3 of A240192.

Formula

Empirical: a(n) = 9*a(n-1) - 27*a(n-2) + 29*a(n-3) + 6*a(n-4) - 32*a(n-5) + 16*a(n-6) for n>9.

Empirical g.f.: x*(3 - 15*x + 10*x^2 + 33*x^3 - 50*x^4 + 40*x^5 - 25*x^6 - 52*x^7 + 72*x^8) / ((1 - x)*(1 - 2*x)*(1 - 6*x + 7*x^2 + 4*x^3 - 8*x^4)). - Colin Barker, Oct 27 2018