A189884 Number of 1:4:sqrt(17) proportioned triangles on a (n+1) X (n+1) grid.

0, 0, 0, 32, 96, 192, 320, 560, 912, 1368, 1920, 2712, 3728, 4960, 6400, 8256, 10480, 13064, 16000, 19600, 23736, 28408, 33608, 39768, 46680, 54344, 62744, 72448, 83152, 94864, 107568, 121968, 137648, 154624, 172880, 193296, 215304, 238920, 264136

Offset

1,4

Links

R. H. Hardin, Table of n, a(n) for n = 1..115

Formula

Empirical: a(n) = a(n-1) +2*a(n-4) -2*a(n-5) -a(n-8) +a(n-9) +a(n-16) -a(n-18) -2*a(n-20) +2*a(n-22) +a(n-24) -a(n-26) -a(n-33) +a(n-34) +2*a(n-37) -2*a(n-38) -a(n-41) +a(n-42)

Example

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

Crossrefs

Main diagonal of A189885.

Sequence in context: A362841 A044219 A044600 * A175165 A281237 A197604

Adjacent sequences: A189881 A189882 A189883 * A189885 A189886 A189887

Keyword

nonn

Author

R. H. Hardin, Apr 29 2011

Status

approved