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A320542
a(n) is the number of ways to select 3 distinct points forming a triangle of unsigned area = n from a square of grid points with side length n, divided by 4.
2
0, 2, 12, 33, 74, 258, 294, 661, 1258, 1940, 2044, 5254, 4136, 7738, 12902, 13357, 13142, 29540, 21214, 40816, 50388, 50012, 47680, 101662, 83684, 99690, 140638, 158568, 126720, 282042, 167514, 253779, 318556, 302230, 386186, 579833, 350556, 478058, 629582, 765498
OFFSET
1,2
COMMENTS
Let s(n) be the number of ways to select 3 different points from a square of grid points with side length n such that they form a triangle with absolute area n, then a(n) = s(n)/4. Permutations of the vertices are considered equivalent.
CROSSREFS
KEYWORD
nonn
AUTHOR
Hugo Pfoertner, Oct 15 2018
EXTENSIONS
a(35)-a(40) from Giovanni Resta, Oct 26 2018
STATUS
approved