OFFSET
1,4
COMMENTS
LINKS
Heinrich Ludwig, Table of n, a(n) for n = 1..129
EXAMPLE
The triangle begins:
1;
1, 1;
2, 4, 3, 1;
3, 10, 19, 22, 7, 1;
4, 22, 75, 170, 204, 115, 18, 1;
5, 41, 218, 816, 1891, 2635, 1909, 628, 58, 3;
7, 72, 542, 2947, 10846, 26695, 41770, 39218, 19905, 4776, 437, 13;
...
There is exactly T(5, 8) = 1 way to place 8 points (x) on a triangular grid of side 5 according to the definition of the sequence:
.
x x
x . x
x . . x
x . . . x
CROSSREFS
KEYWORD
nonn,tabf
AUTHOR
Heinrich Ludwig, May 30 2014
STATUS
approved