A091123 - OEIS

A091123

Number of primes of the form 7k+4 less than 10^n.

0, 3, 26, 202, 1601, 13069, 110776, 960085, 8474021, 75841922, 686340737, 6267984796, 57677570801, 534156825708, 4974095076052, 46539723002447, 437259524381692, 4123325709519055, 39009611201920476

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OFFSET

1,2

COMMENTS

Computed by T. D. Noe, Dec 19 2003.

LINKS

Table of n, a(n) for n=1..19.

Eric Weisstein's World of Mathematics, Modular Prime Counting Function

MATHEMATICA

p = Select[Table[7 i + 4, {i, 0, 10^7}], PrimeQ[#] &]; Table[Count[p, x_ /; x < 10^n], {n, 7}] (* Robert Price, May 28 2019 *)

CROSSREFS

Cf. A091120, A091121, A091122, A091124, A091125.

Sequence in context: A121121 A355047 A228116 * A395885 A395886 A395887

Adjacent sequences: A091120 A091121 A091122 * A091124 A091125 A091126

KEYWORD

nonn,more

AUTHOR

Eric W. Weisstein, Dec 19 2003

EXTENSIONS

a(10) from Robert G. Wilson v, Dec 22 2003

a(11)-a(14) from Hiroaki Yamanouchi, Oct 14 2014

a(15)-a(19) from Benjamin Chaffin, Jun 02 2026

a(19) corrected by Benjamin Chaffin, Jul 08 2026

STATUS

approved