%I A000050 M0715 N0265
%S A000050 1,2,3,5,9,16,29,54,97,180,337,633,1197,2280,4357,8363,16096,31064,60108,
%T A000050 116555,226419,440616,858696,1675603,3273643,6402706,12534812,24561934,
               48168461,
%U A000050 94534626,185661958,364869032,717484560,1411667114,2778945873,5473203125
%N A000050 Number of positive integers <= 2^n of form x^2 + y^2.
%D A000050 P. Moree and H. J. J. te Riele, The hexagonal versus the square lattice, 
               Math. Comp. 73 (2004), no. 245, 451-473.
%D A000050 D. Shanks and L. P. Schmid, Variations on a theorem of Landau. Part I, 
               Math. Comp., 20 (1966), 551-569.
%D A000050 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 
               (includes this sequence).
%D A000050 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%H A000050 P. Moree and H. J. J. te Riele, <a href="http://arXiv.org/abs/math.NT/
               0204332">The hexagonal versus the square lattice</a>
%H A000050 <a href="Sindx_Qua.html#quadpop">Index entries for sequences related 
               to populations of quadratic forms</a>
%Y A000050 Sequence in context: A000691 A103285 A000049 this_sequence A050253 A107250 
               A050168
%Y A000050 Adjacent sequences: A000047 A000048 A000049 this_sequence A000051 A000052 
               A000053
%K A000050 nonn
%O A000050 0,2
%A A000050 N. J. A. Sloane (njas(AT)research.att.com).