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 A065607 #8 Sep 09 2023 23:19:40 %S A065607 20,40,60,80,100,120,140,156,160,180,200,220,240,255,260,280,300,312, %T A065607 320,340,360,380,400,420,440,460,468,480,500,510,520,540,560,580,600, %U A065607 600,609,620,624,640,660,680,700,720,740,760,765,780,780,800,820,840 %N A065607 Related to reciprocal Pythagorean triples: 1/a(n)^2 + 1/k^2 = 1/j^2 has an integer solution (k,j) with k<a(n). %C A065607 The entries 600 and 780 occur in two solutions each; the others entries uniquely. %p A065607 a := []; for n from 2 to 1000 do for m from 2 to n do if (numer(simplify(1/n^2+1/m^2))=1) then if type(sqrt(denom(simplify(1/n^2+1/m^2))), integer)=true then print(n, m, ifactor(n), ifactor(m), ifactor(denom(simplify(1/n^2+1/m^2))), sqrt(denom(simplify(1/n^2+1/m^2)))); a := [op(a), n]; fi fi od od; print(a); %K A065607 nonn %O A065607 1,1 %A A065607 _Len Smiley_, Dec 01 2001 %E A065607 Offset corrected by _Sean A. Irvine_, Sep 09 2023