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 A384288 #43 Jul 22 2025 18:13:23 %S A384288 12,84,312,840,1860,3612,6384,10512,16380,24420,35112,48984,66612, %T A384288 88620,115680,148512,187884,234612,289560,353640,427812,513084,610512, %U A384288 721200,846300,987012,1144584,1320312,1515540,1731660,1970112,2232384,2520012,2834580 %N A384288 Length of the long leg in the unique primitive Pythagorean triple whose inradius is A002378(n) and such that its long leg and its hypotenuse are consecutive natural numbers. %H A384288 José Miguel Blanco Casado and Miguel-Ángel Pérez García-Ortega, <a href="/A383834/a383834.pdf">El Libro de las Ternas Pitagóricas</a> %F A384288 a(n) = 2 * A002378(n) * (A002378(n) + 1). %e A384288 Triangles begin: %e A384288 n=1: 5, 12, 13; %e A384288 n=2: 13, 84, 85; %e A384288 n=3: 25, 312, 313; %e A384288 ... %e A384288 This sequence gives the middle column. %Y A384288 Cf. A002378 (inradius), A001844 (short leg), A008514 (sum of the legs), A237516 (semiperimeter), A384566 (area). %K A384288 nonn,easy %O A384288 1,1 %A A384288 _Miguel-Ángel Pérez García-Ortega_, May 31 2025