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 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, 139619172018237 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Computed by T. D. Noe, Dec 19 2003. LINKS Table of n, a(n) for n=1..16. 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 A369421 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 a(16) from Griffin N. Macris, Jan 18 2023 STATUS approved

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Last modified August 12 09:11 EDT 2024. Contains 375085 sequences. (Running on oeis4.)