A091119 Number of primes of the form 6k+5 less than 10^n.

1, 12, 86, 616, 4806, 39265, 332383, 2880936, 25424819, 227529386, 2059036143, 18803978496, 173032844824, 1602471005226, 14922285950519, 139619172018237

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