%I #6 Mar 30 2012 18:38:56
%S 1,2,3,4,5,9,10,11,12,13,14,15,16,17,21,22,23,27,28,29,30,31,32,63,64,
%T 65,88,89,90,91,92,93,94,95,96,97,98,99,105,106,107,108,109,136,137,
%U 138,139,140,141,142,143,144,145,146,147,189,190,191,192,193,194,195
%N Numbers n such that A068589(n) is a perfect square.
%o (PARI) precision 1000 digits : for(n=1,300,if(sqrt(denominator(sum(i=1,n,1/i^3))/denominator(sum(i=1,n,1/i))) == floor(sqrt(denominator(sum(i=1,n,1/i^3))/denominator(sum(i=1,n,1/i)))),print1(n,",")))
%K easy,nonn
%O 1,2
%A _Benoit Cloitre_, Apr 07 2002
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