A221315 Number of nonnegative integer arrays of length n summing to n without equal adjacent values modulo 2.

1, 0, 3, 8, 5, 0, 28, 72, 45, 0, 286, 728, 455, 0, 3060, 7752, 4845, 0, 33649, 85008, 53130, 0, 376740, 950040, 593775, 0, 4272048, 10759232, 6724520, 0, 48903492, 123047496, 76904685, 0, 563921995, 1417861016, 886163135, 0, 6540715896, 16435645072

Offset: 1

Author

R. H. Hardin Jan 10 2013

Keywords

• nonn

Comments

Column 2 of A221321

Solutions must alternate even-odd, and cannot have an odd number of those pairs for even n, so a(n)=0 for n modulo 4 = 2

Examples

			All solutions for n=5
..1....1....1....1....3
..0....0....0....2....0
..3....1....1....1....1
..0....0....2....0....0
..1....3....1....1....1
		

Links

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