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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). 5

%I

%S 20,40,60,80,100,120,140,156,160,180,200,220,240,255,260,280,300,312,

%T 320,340,360,380,400,420,440,460,468,480,500,510,520,540,560,580,600,

%U 600,609,620,624,640,660,680,700,720,740,760,765,780,780,800,820,840

%N 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 The entries 600 and 780 occur in two solutions each; the others entries uniquely.

%p 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 nonn

%O 0,1

%A _Len Smiley_, Dec 01 2001

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Last modified September 18 20:10 EDT 2021. Contains 347534 sequences. (Running on oeis4.)