The OEIS is supported by the many generous donors to the OEIS Foundation.

 Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A091119 Number of primes of the form 6k+5 less than 10^n. 1
 1, 12, 86, 616, 4806, 39265, 332383, 2880936, 25424819, 227529386, 2059036143, 18803978496, 173032844824, 1602471005226, 14922285950519 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Computed by T. D. Noe, Dec 19 2003. LINKS Eric Weisstein's World of Mathematics, Modular Prime Counting Function FORMULA a(n) = A091116(n) - 1. a(n) = A006880(n) - 2 - A091115(n). - R. J. Mathar, Jul 20 2007 MATHEMATICA p = Select[Table[6 i + 5, {i, 0, 10^7}], PrimeQ[#] &]; Table[Count[p, x_ /; x < 10^n], {n, 7}] (* Robert Price, May 29 2019 *) PROG (PARI) a(n) = sum(k=0, 10^n\6-1, isprime(6*k+5)); \\ Jinyuan Wang, Aug 04 2019 CROSSREFS Cf. A007528, A091116. Sequence in context: A098206 A104911 A283119 * A243248 A046023 A183721 Adjacent sequences: A091116 A091117 A091118 * A091120 A091121 A091122 KEYWORD nonn,more AUTHOR Eric W. Weisstein, Dec 19 2003 EXTENSIONS a(10) from Robert G. Wilson v, Dec 22 2003 a(11)-a(13) from Jinyuan Wang, Aug 04 2019 a(14)-a(15) from Griffin N. Macris, Sep 13 2020 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified November 28 09:43 EST 2022. Contains 358407 sequences. (Running on oeis4.)