A190094 Number of rhombuses on a (n+1) X 6 grid.

5, 20, 50, 96, 151, 212, 273, 344, 421, 504, 587, 676, 765, 860, 959, 1064, 1169, 1280, 1391, 1508, 1625, 1748, 1871, 2000, 2131, 2268, 2405, 2548, 2691, 2840, 2989, 3144, 3299, 3460, 3621, 3788, 3955, 4128, 4301, 4480, 4659, 4844, 5029, 5220, 5411, 5608

Offset

1,1

Links

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

Formula

Empirical: a(n) = 2*a(n-1) - 2*a(n-3) + a(n-4) for n>27.

Example

Some solutions for n=3:
..1..2....1..0....1..3....1..4....0..4....0..3....0..1....1..3....0..0....2..0
..1..4....1..2....1..5....1..5....1..3....1..1....0..3....2..1....0..2....2..1
..3..4....3..2....3..5....2..5....2..4....3..2....2..3....3..3....2..2....3..1
..3..2....3..0....3..3....2..4....1..5....2..4....2..1....2..5....2..0....3..0

Crossrefs

Column 5 of A190098.

Sequence in context: A005287 A147488 A297569 * A134481 A358632 A062158

Adjacent sequences: A190091 A190092 A190093 * A190095 A190096 A190097

Keyword

nonn

Author

R. H. Hardin, May 04 2011

Status

approved