This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A052435 a(n) = round(li(n) - pi(n)), where li is the logarithmic integral and pi(x) is the number of primes up to x. 10
 0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 2, 1, 2, 2, 3, 2, 2, 2, 2, 2, 3, 2, 2, 3, 3, 3, 3, 3, 3, 2, 3, 3, 3, 3, 4, 3, 3, 4, 4, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 3, 3, 4, 4, 4, 4, 4, 4, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 3, 3, 4, 4, 4, 4, 3, 4, 4, 4, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 4, 5, 5, 5, 4, 5, 4 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,8 COMMENTS Eventually contains negative terms! The logarithmic integral is the "American" version starting at 0. The first crossover (P. Demichel) is expected to be around 1.397162914*10^316. - Daniel Forgues, Oct 29 2011 LINKS Harry J. Smith, Table of n, a(n) for n = 2..20000 C. Caldwell, How many primes are there? Patrick Demichel, The prime counting function and related subjects, April 05, 2005, 75 pages. Eric Weisstein's World of Mathematics, Prime Counting Function Eric Weisstein's World of Mathematics, Logarithmic Integral Eric Weisstein's World of Mathematics, Skewes Number MATHEMATICA Table[Round[LogIntegral[x]-PrimePi[x]], {x, 2, 100}] PROG (PARI) a(n)=round(real(-eint1(-log(n)))-primepi(n)) \\ Charles R Greathouse IV, Oct 28 2011 (MAGMA) [Round(LogIntegral(n) - #PrimesUpTo(n)): n in [2..105]]; // G. C. Greubel, May 17 2019 (Sage) [round(li(n) - prime_pi(n)) for n in (2..105)] # G. C. Greubel, May 17 2019 CROSSREFS Cf. A052434. Sequence in context: A063982 A318882 A055020 * A094701 A210452 A240301 Adjacent sequences:  A052432 A052433 A052434 * A052436 A052437 A052438 KEYWORD sign,look 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 July 17 15:19 EDT 2019. Contains 325106 sequences. (Running on oeis4.)