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 A383957 #21 Jul 13 2025 17:24:49
%S A383957 7,7,17,71,449,3697,35377,369799,4095521,47297537,564278417,
%T A383957 6911822737,86538816337,1103803791601,14305269324961,187980077927431,
%U A383957 2500329797088481,33615543666867361,456277457385934801,6246438372527004961,86175353802778434481,1197196443885744428881,16738118900659230353761
%N A383957 Sum of the legs of the unique primitive Pythagorean triple whose inradius is A000108(n) and such that its long leg and its hypotenuse are consecutive natural numbers.
%H A383957 José Miguel Blanco Casado and Miguel-Ángel Pérez García-Ortega, <a href="/A383834/a383834.pdf">El Libro de las Ternas Pitagóricas</a>
%F A383957 a(n) = A383251(n,1) + A383251(n,2).
%F A383957 a(n) = 2*(A000108(n))^2 + 4*A000108(n) + 1.
%e A383957 For n=1, the short leg is A383251(1,1) = 3 and the long leg is A383251(1,2) = 4 so the sum of the legs is then a(1) = 3 + 4 = 7.
%t A383957 a=Table[(2n)!/(n!(n+1)!),{n,0,23}];Apply[Join,Map[{2#^2+4#+1}&,a]]
%Y A383957 Cf. A000108, A383251, A381483, A382114, A006007, A058919, A336535.
%K A383957 nonn,easy
%O A383957 0,1
%A A383957 _Miguel-Ángel Pérez García-Ortega_, May 16 2025