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A047785
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a(n) = ceiling(Li(n)).
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3
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2, 3, 3, 4, 5, 5, 6, 6, 7, 7, 8, 8, 8, 9, 9, 9, 10, 10, 10, 11, 11, 11, 12, 12, 12, 13, 13, 13, 14, 14, 14, 14, 15, 15, 15, 16, 16, 16, 16, 17, 17, 17, 17, 18, 18, 18, 18, 19, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21, 22, 22, 22, 22, 23, 23, 23, 23, 24
(list;
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refs;
listen;
history;
text;
internal format)
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OFFSET
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2,1
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REFERENCES
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M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math. Series 55, 1964 (and various reprintings), p. 238.
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LINKS
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M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, 1972 [alternative scanned copy].
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FORMULA
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a(n) = ceiling(logarithmic integral(n)). - G. C. Greubel, May 17 2019
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MATHEMATICA
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PROG
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(PARI) vector(80, n, n++; ceil(real(-eint1(-log(n)))) ) \\ G. C. Greubel, May 17 2019
(Magma) [Ceiling(LogIntegral(n)): n in [2..80]]; // G. C. Greubel, May 17 2019
(Sage) [ceil(li(n)) for n in (2..80)] # G. C. Greubel, May 17 2019
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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