This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A155154 #17 Jul 02 2021 16:45:19 %S A155154 0,3,14,33,62,101,148,207,276,353,448,547,662,785,920,1067,1230,1397, %T A155154 1586,1773,1986,2205,2436,2671,2940,3207,3494,3787,4096,4399,4764, %U A155154 5095,5458,5825,6208,6603,7050,7453,7880,8331,8826,9277,9800,10279,10808 %N A155154 Number of right triangles with nonnegative integer coordinates less than or equal to n and one corner at the origin. %H A155154 Project Euler, <a href="https://projecteuler.net/problem=91">Problem 91: Right triangles with integer coordinates</a>. %o A155154 (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 %K A155154 nonn %O A155154 0,2 %A A155154 Emlyn Corrin (emlyn(AT)corrin.name), Jan 21 2009