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

0,2

Links

Table of n, a(n) for n=0..44.

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

Prog

(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

Crossrefs

Sequence in context: A197946 A130697 A033991 * A081269 A140064 A064226

Adjacent sequences: A155151 A155152 A155153 * A155155 A155156 A155157

Keyword

nonn

Author

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

Status

approved