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a(n) = number of times n^2*k^2/(n^2+k^2) is an integer as k ranges over 0, 1, 2, ...
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%I #5 Mar 30 2012 18:38:58

%S 1,2,1,2,2,2,1,2,1,6,1,2,1,2,3,2,2,2,1,7,1,2,1,2,2,4,1,2,1,8,1,2,1,3,

%T 2,2,2,2,2,7,1,2,1,2,3,2,1,2,1,7,2,4,1,2,2,2,1,4,1,9,1,2,1,2,5,2,1,4,

%U 1,7,1,2,1,3,3,2,1,5,1,7,1,3,1,2,4,2,1,2,1,8,1,2,1,2,2,2,1,2,1,8,2,4,1,4,3

%N a(n) = number of times n^2*k^2/(n^2+k^2) is an integer as k ranges over 0, 1, 2, ...

%C A018892(n) gives the number of integers of the form nk/(n+k).

%o (PARI) for(n=1,150,print1(sum(i=0,n^2,if((n^2*i^2)%(n^2+i^2),0,1)),","))

%Y Cf. A066451.

%K easy,nonn

%O 1,2

%A _Benoit Cloitre_, May 10 2002