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%I M1021 N0384 #22 Mar 15 2014 05:14:52
%S 1,2,4,6,11,19,34,63,117,218,411,780,1487,2849,5477,10562,20419,39563,
%T 76805,149360,290896,567321,1107775,2165487,4237384,8299283,16268639,
%U 31915437,62656158,123088460,241958676,475901501,936544684
%N Related to population of numbers of form x^2 + y^2.
%C Shanks' paper gives erroneous value a(16)=10555. - _Sean A. Irvine_, Feb 25 2011
%D N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H D. Shanks, <a href="http://dx.doi.org/10.1090/S0025-5718-1964-0159174-9">The second-order term in the asymptotic expansion of B(x)</a>, Mathematics of Computation 18 (1964), pp. 75-86.
%H <a href="/index/Qua#quadpop">Index entries for sequences related to populations of quadratic forms</a>
%p Digits:=500;
%p K:=.764223653589220662990698731250092328116790541393409514721686673
%p 7496146416587328588384015050131312337219372691207925926341874206467
%p 8084323063315434629380531605171169636177508819961243824994277683469
%p 0516235139218719620569053295644670419176349770659569905712938660289
%p 3858998296105166296089099177929836072973697200640316985128636517347
%p 3921065768550978681981674707359066921;
%p a:=n->round(evalf((2/3)*K*int(1/sqrt(ln(t)), t=1..2^n)));
%p # _Sean A. Irvine_, Feb 25 2011
%Y Cf. A000691.
%K nonn
%O 1,2
%A _N. J. A. Sloane_
%E More terms from _Sean A. Irvine_, Feb 24 2011
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