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 A380301 #9 Feb 03 2025 23:09:28
%S A380301 20,42,72,156,210,342,420,600,930,1056,1482,1806,1980,2352,2970,3660,
%T A380301 3906,4692,5256,5550,6480,7140,8190,9702,10506,10920,11772,12210,
%U A380301 13110,16512,17556,19182,19740,22650,23256,25122,27060,28392,30450,32580,33306,37056,37830,39402
%N A380301 Semiperimeter of the unique primitive Pythagorean triple whose inradius is the n-th odd prime and whose short leg is an even number.
%D A380301 Miguel Ángel Pérez García-Ortega, José Manuel Sánchez Muñoz and José Miguel Blanco Casado, El Libro de las Ternas Pitagóricas, Preprint 2025.
%H A380301 Miguel-Ángel Pérez García-Ortega, <a href="/A380301/a380301.pdf">El Libro de las Ternas Pitagóricas</a>
%F A380301 a(n) = ( A367335(n,1) + A367335(n,2) + A367335(n,3) )/2.
%t A380301 a = Table[Prime[n], {n, 2, 54}]; Apply[Join, Map[{#^2 + 3 # + 2} &, a]]
%Y A380301 Cf. A367335, A377016, A378380, A378965, A379506.
%K A380301 nonn,easy
%O A380301 0,1
%A A380301 _Miguel-Ángel Pérez García-Ortega_, Jan 19 2025