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%I #12 Nov 06 2015 15:26:57
%S 21,24,26,27,28,30,31,33,35,36,37,39,42,43,45,47,50,51,52,55,56,58,60,
%T 61,62,63,64,66,67,71,74,75,76,77,79,81,83,85,86,88,90,91,93,94,95,96,
%U 98,99,100,102,103,105,106,107,108,109,110,112,113,115,116,120,121,122,123,124,125,126,127,128,129,130,131,132,133,137,138,141,143,145,147,148,149,150
%N Positive integers N such that there is a triangle with rational sides having area and perimeter both equal N.
%C A positive integer N is in the sequence if and only if there exist positive rational numbers x,y such that x*y>1 and 4*x*y*(x+y)/(x*y-1)=N.
%C Except for N=27, a positive integer N is in this sequence if and only if N>20 and the elliptic curve w^2 = u^3 + N^2*(u+64)^2 has positive rank.
%Y Cf. A135412, A206334, A228914, A117319, A228380.
%K nonn
%O 1,1
%A _Thomas Bokk_, Nov 05 2015
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