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 A308635 #11 Jun 12 2019 16:27:04 %S A308635 169219,1370269,5965699,15227879,17750981,19342559,21828601,24861761, %T A308635 27379621,34602049,39844619,48719711,50049281,51649019,52187371, %U A308635 52816609,58026659,73659239,79782821,86569771,91316801,96842831,104572009 %N A308635 Sequence of 4 Pythagorean triangles, each with a leg and hypotenuse prime. The hypotenuse of each triangle is the leg of the next triangle. %H A308635 Ray Chandler, <a href="/A308635/b308635.txt">Table of n, a(n) for n = 1..2625</a> %H A308635 H. Dubner and T. Forbes, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL4/DUBNER/pyth.html">Prime Pythagorean triangles</a>, J. Integer Seqs., Vol. 4 (2001), #01.2.3. %F A308635 For each p(n), q=(p*p+1)/2, r=(q*q+1)/2, s=(r*r+1)/2, t=(s*s+1)/2 and p, q, r, s, t are all prime. %e A308635 p(1)=169219, q=14317534981, r=102495903966079335181, s=5252705164911878795670904374881472151381, ... %Y A308635 Cf. A048161, A048270, A048295, A308636. Primes in A188547. %K A308635 nonn %O A308635 1,1 %A A308635 _Ray Chandler_, Jun 12 2019