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.

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.

Links

Table of n, a(n) for n=1..40.

Crossrefs

Cf. A115004, A320310, A320540, A320544.

Sequence in context: A106185 A098203 A305330 * A242709 A055707 A055699

Adjacent sequences: A320539 A320540 A320541 * A320543 A320544 A320545

Keyword

nonn

Author

Hugo Pfoertner, Oct 15 2018

Extensions

a(35)-a(40) from Giovanni Resta, Oct 26 2018

Status

approved