A334087 Draw the lines with equations y=kx (k=1..n) on the R^2/Z^2 square flat torus. a(n) is the number of intersection points.

0, 0, 1, 2, 5, 9, 17, 25, 39, 55, 77, 99, 131, 165, 211, 257, 311, 369, 443, 517, 609, 705, 813, 921, 1051, 1185, 1339, 1493, 1665, 1843, 2049, 2255, 2491, 2735, 2999, 3263, 3551, 3845, 4175, 4505, 4859, 5221, 5623, 6025, 6469, 6923, 7401, 7879, 8403, 8935, 9509

Offset: 0

Author

Luc Rousseau, Apr 15 2020

Keywords

• nonn

Comments

It appears that the second differences of this sequence yield A326305.

Links

• Luc Rousseau, Illustration of the fact that a(7) = 25

Crossrefs

Cf. A326305.

Programs

PARI

f(i,j,c,d)=my(L=List(),x,y);x=(d-c)/(j-i);if(max(c/i,d/j)<=x&&x1)+#h(n)
for(n=0,60,print1(a(n), ", "))