A155154 Number of right triangles with nonnegative integer coordinates less than or equal to n and one corner at the origin.

0, 3, 14, 33, 62, 101, 148, 207, 276, 353, 448, 547, 662, 785, 920, 1067, 1230, 1397, 1586, 1773, 1986, 2205, 2436, 2671, 2940, 3207, 3494, 3787, 4096, 4399, 4764, 5095, 5458, 5825, 6208, 6603, 7050, 7453, 7880, 8331, 8826, 9277, 9800, 10279, 10808

Offset: 0

Author

Emlyn Corrin (emlyn(AT)corrin.name), Jan 21 2009

Keywords

• nonn

Links

• Project Euler, Problem 91: Right triangles with integer coordinates.

Programs

PARI

a(n)=3*n^2+sum(a=1, n, sum(b = 1, n, 2*min(b*gcd(a, b)\a, (n - a)*gcd(a, b)\b) ) ) \\ Yurii Ivanov, Jun 25 2021