A047784 - OEIS

A047784

Nearest integer to Li(n).

1, 2, 3, 4, 4, 5, 5, 6, 6, 7, 7, 7, 8, 8, 9, 9, 9, 10, 10, 10, 11, 11, 11, 12, 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

(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

G. C. Greubel, Table of n, a(n) for n = 2..10000

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) = round(logarithmic integral(n)). - G. C. Greubel, May 16 2019

MATHEMATICA

Table[Round[LogIntegral[n]], {n, 2, 80}] (* G. C. Greubel, May 16 2019 *)

PROG

(PARI) vector(80, n, n++; round(real(-eint1(-log(n)))) ) \\ G. C. Greubel, May 16 2019

(Magma) [Round(LogIntegral(n)): n in [2..80]]; // G. C. Greubel, May 16 2019

(Sage) [round(li(n)) for n in (2..80)] # G. C. Greubel, May 16 2019

CROSSREFS

Cf. A047783 (floor), A047785 (ceiling).

Sequence in context: A094192 A093874 A047741 * A047742 A302778 A203967

Adjacent sequences: A047781 A047782 A047783 * A047785 A047786 A047787

KEYWORD

nonn

AUTHOR

N. J. A. Sloane

STATUS

approved