|
%I #15 Sep 08 2022 08:44:57
%S 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,
%T 14,14,14,14,15,15,15,16,16,16,16,17,17,17,17,18,18,18,18,19,19,19,19,
%U 20,20,20,20,21,21,21,21,22,22,22,22,23,23,23,23,24
%N a(n) = ceiling(Li(n)).
%D 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.
%H Harvey P. Dale, <a href="/A047785/b047785.txt">Table of n, a(n) for n = 2..1000</a>
%H M. Abramowitz and I. A. Stegun, eds., <a href="http://www.convertit.com/Go/ConvertIt/Reference/AMS55.ASP">Handbook of Mathematical Functions</a>, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, 1972 [alternative scanned copy].
%F a(n) = ceiling(logarithmic integral(n)). - _G. C. Greubel_, May 17 2019
%t Ceiling[LogIntegral[Range[2,70]]] (* _Harvey P. Dale_, Dec 29 2012 *)
%o (PARI) vector(80, n, n++; ceil(real(-eint1(-log(n)))) ) \\ _G. C. Greubel_, May 17 2019
%o (Magma) [Ceiling(LogIntegral(n)): n in [2..80]]; // _G. C. Greubel_, May 17 2019
%o (Sage) [ceil(li(n)) for n in (2..80)] # _G. C. Greubel_, May 17 2019
%Y Cf. A047783 (floor), A047784 (round).
%K nonn
%O 2,1
%A _N. J. A. Sloane_
|
