A189327 Number of nondecreasing arrangements of 4 numbers in 0..n with the last equal to n and each after the second equal to the sum of one or two of the preceding four.

2, 6, 7, 12, 12, 18, 17, 24, 22, 30, 27, 36, 32, 42, 37, 48, 42, 54, 47, 60, 52, 66, 57, 72, 62, 78, 67, 84, 72, 90, 77, 96, 82, 102, 87, 108, 92, 114, 97, 120, 102, 126, 107, 132, 112, 138, 117, 144, 122, 150, 127, 156, 132, 162, 137, 168, 142, 174, 147, 180, 152, 186, 157

Offset: 1

Author

R. H. Hardin Apr 20 2011

Keywords

• nonn

Comments

Row 2 of A189326

Examples

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

Links

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

Formula

Empirical: a(n) = 2*a(n-2) -a(n-4)