The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A047783 a(n) = floor(Li(n)). 5
 1, 2, 2, 3, 4, 4, 5, 5, 6, 6, 7, 7, 7, 8, 8, 8, 9, 9, 9, 10, 10, 10, 11, 11, 11, 12, 12, 12, 13, 13, 13, 13, 14, 14, 14, 15, 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,2 REFERENCES 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. LINKS Robert G. Wilson v, Table of n, a(n) for n = 2..1000 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]. FORMULA a(n) = floor(logarithmic integral(n)). - G. C. Greubel, May 17 2019 MATHEMATICA Array[Floor[LogIntegral[#]] &, 70, 2] (* Robert G. Wilson v, Feb 23 2017 *) PROG (PARI) vector(80, n, n++; floor(real(-eint1(-log(n)))) ) \\ G. C. Greubel, May 17 2019 (MAGMA) [Floor(LogIntegral(n)): n in [2..80]]; // G. C. Greubel, May 17 2019 (Sage) [floor(li(n)) for n in (2..80)] # G. C. Greubel, May 17 2019 CROSSREFS Cf. A047784 (round), A047785 (ceiling). Sequence in context: A227737 A194177 A023190 * A321667 A194212 A194208 Adjacent sequences:  A047780 A047781 A047782 * A047784 A047785 A047786 KEYWORD nonn AUTHOR STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified September 27 03:21 EDT 2020. Contains 337380 sequences. (Running on oeis4.)