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Search: id:A000691
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| A000691 |
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Ramanujan's approximation to population of x^2 + y^2.
(Formerly M0713 N0263)
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+0
2
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| 1, 2, 3, 5, 9, 16, 29, 52, 94, 175, 327, 616, 1169, 2231, 4273, 8215, 15842, 30628, 59345, 115208, 224040, 436343, 850981, 1661663, 3248231, 6356076, 12448925, 24402959, 47873156, 93984236, 184632691, 362938014, 713852258, 1404817021
(list; graph; listen)
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OFFSET
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0,2
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REFERENCES
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D. Shanks, The second-order term in the asymptotic expansion of B(x), Math. Comp., 18 (1964), 75-86.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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Index entries for sequences related to populations of quadratic forms
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MAPLE
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K:=.764223653589220662990698731250092328116790541393409514721686673\
7496146416587328588384015050131312337219372691207925926341874206467\
8084323063315434629380531605171169636177508819961243824994277683469\
0516235139218719620569053295644670419176349770659569905712938660289\
3858998296105166296089099177929836072973697200640316985128636517347\
3921065768550978681981674707359066921; a:=n->round(evalf(K*int(1/sqrt(ln(t)), t=1..2^n)));
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CROSSREFS
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Sequence in context: A006788 A054650 A022857 this_sequence A103285 A000049 A000050
Adjacent sequences: A000688 A000689 A000690 this_sequence A000692 A000693 A000694
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
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More terms and Maple program from Salvador Perez (pies314(AT)hotmail.com), May 08 2005
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