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
KEYWORD
nonn
AUTHOR
STATUS
approved