%I A000690 M0586 N0212
%S A000690 1,2,3,4,7,13,24,44,83,157,297,567,1085,2086,4019,7766,15039,29181,
%T A000690 56717,110408,215225,420076,820836,1605587,3143562,6160098,12080946
%N A000690 Landau's approximation to population of x^2 + y^2.
%D A000690 D. Shanks, The second-order term in the asymptotic expansion of B(x), 
               Math. Comp., 18 (1964), 75-86.
%D A000690 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 
               (includes this sequence).
%D A000690 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%H A000690 <a href="Sindx_Qua.html#quadpop">Index entries for sequences related 
               to populations of quadratic forms</a>
%Y A000690 Sequence in context: A096723 A137495 A099779 this_sequence A049876 A049795 
               A014251
%Y A000690 Adjacent sequences: A000687 A000688 A000689 this_sequence A000691 A000692 
               A000693
%K A000690 nonn
%O A000690 0,2
%A A000690 N. J. A. Sloane (njas(AT)research.att.com).