A163568 Floor of the integral of x/log(x) for x=2 to 10^n.

27, 1243, 78624, 5762206, 455055611, 37607950277, 3204942065688, 279238344248553, 24739954309690412, 2220819602783663480, 201467286691248261495, 18435599767366347775141, 1699246750872593033005720, 157589269275974838158399968, 14692398897720447639079087666

Offset

1,1

Comments

This integral is an approximation to the sum of x/log(x) for x=2 to 10^n and closely approximates Pi(n^2) for x = 2 to n.

Links

Alois P. Heinz, Table of n, a(n) for n = 1..200

Mathematica

Table[Floor[NIntegrate[x/Log[x], {x, 2, 10^n}]], {n, 1, 10}] (* G. C. Greubel, Jul 28 2017 *)

Prog

(PARI) g(n)=intnum(x=2, 10^n, x/log(x)); for(x=1, 20, print1(floor(g(x))", "))

Crossrefs

Cf. A163521.

Sequence in context: A357228 A104206 A327596 * A066300 A273518 A075547

Adjacent sequences: A163565 A163566 A163567 * A163569 A163570 A163571

Keyword

nonn

Author

Cino Hilliard, Jul 30 2009

Extensions

Edited (but not checked) by N. J. A. Sloane, Aug 01 2009

Offset and upper limit in the definition corrected by R. J. Mathar, Aug 02 2009

Status

approved