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 A072289 #11 Sep 23 2024 13:41:02 %S A072289 1,85,230,1054,205,5405,6510,18615,27335,44556,45034,22660,89531, %T A072289 152889,181220,53430,221595,304265,246380,720291,360910,595884,811954, %U A072289 1444915,1362295,40630,2504645,1304445,2385474,3311396,3647810,2420665,1641809 %N A072289 One eighty-fourth the area of primitive Pythagorean triangles with (increasing) square hypotenuses (precisely those of A008846). %C A072289 For Pythagorean triples (x, y, z) satisfying x^2 + y^2 = z^2, we have 3 and 4 dividing either of x or y and 7 dividing x, y or (x^2 - y^2), so that 3*4*7 always divide x*y*(x^2 - y^2); if (x, y) be themselves the generators of another Pythagorean triple, (x^2 - y^2, 2*x*y, x^2 + y^2=z^2), the corresponding primitive Pythagorean triangle has area x*y*(x^2 - y^2) and is hence divisible by 84. %Y A072289 Cf. A020882. %K A072289 nonn %O A072289 1,2 %A A072289 _Lekraj Beedassy_, Jul 11 2002 %E A072289 Corrected and extended by _Ray Chandler_, Oct 28 2003 %E A072289 Sorted by increasing square hypotenuse, then increasing area by _Sean A. Irvine_, Sep 20 2024