A190112 Number of 2:3:sqrt(13) proportioned triangles on a (n+1)X(n+1) grid

0, 0, 16, 48, 120, 248, 440, 736, 1152, 1720, 2464, 3440, 4672, 6192, 8080, 10344, 13040, 16264, 20024, 24376, 29456, 35248, 41832, 49360, 57808, 67280, 77936, 89760, 102840, 117392, 133376, 150888, 170184, 191200, 214048, 239016, 266024, 295184

Offset

1,3

Comments

Diagonal of A190113

Links

R. H. Hardin, Table of n, a(n) for n = 1..99

Formula

Empirical: a(n) = a(n-1) +2*a(n-3) -2*a(n-4) -a(n-6) +a(n-7) +a(n-9) -a(n-10) -2*a(n-12) +3*a(n-13) -a(n-14) +a(n-15) -3*a(n-16) +2*a(n-17) +a(n-19) -a(n-20) -a(n-22) +a(n-23) +2*a(n-25) -2*a(n-26) -a(n-28) +a(n-29)

Example

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

Crossrefs

Sequence in context: A098322 A175164 A331772 * A211576 A211590 A211584

Adjacent sequences: A190109 A190110 A190111 * A190113 A190114 A190115

Keyword

nonn

Author

R. H. Hardin May 04 2011

Status

approved