A040014 -id:A040014 - cp's OEIS frontend

A006880 Number of primes < 10^n.

0, 4, 25, 168, 1229, 9592, 78498, 664579, 5761455, 50847534, 455052511, 4118054813, 37607912018, 346065536839, 3204941750802, 29844570422669, 279238341033925, 2623557157654233, 24739954287740860, 234057667276344607, 2220819602560918840, 21127269486018731928, 201467286689315906290

Offset: 0

N. J. A. Sloane and Simon Plouffe

Number of primes with at most n digits; or pi(10^n).
Partial sums of A006879. - Lekraj Beedassy, Jun 25 2004
Also omega( (10^n)! ), where omega(x): number of distinct prime divisors of x. - Cino Hilliard, Jul 04 2007
This sequence also gives a good approximation for the sum of primes less than 10^(n/2). This is evident from the fact that the number of primes less than 10^2n closely approximates the sum of primes less than 10^n. See link on Sum of Primes for the derivation. - Cino Hilliard, Jun 08 2008
It appears that (10^n)/log((n+3)!) is a lower bound close to a(n), see A025201. - Eric Desbiaux, Jul 20 2010, edited by M. F. Hasler, Dec 03 2018

John H. Conway and Richard K. Guy, The Book of Numbers, New York: Springer-Verlag, 1996. See pp. 143, 146.
Richard Crandall and Carl B. Pomerance, Prime Numbers: A Computational Perspective, Springer, NY, 2001; p. 11.
Keith Devlin, Mathematics: The New Golden Age, new and revised edition. New York: Columbia University Press (1993): p. 6, Table 1.
Marcus du Sautoy, The Music of the Primes, Fourth Estate / HarperCollins, 2003; p. 48.
Calvin T. Long, Elementary Introduction to Number Theory. Prentice-Hall, Englewood Cliffs, NJ, 1987, p. 77.
Paulo Ribenboim, The Book of Prime Number Records. Springer-Verlag, NY, 2nd ed., 1989, p. 179.
H. Riesel, "Prime numbers and computer methods for factorization," Progress in Mathematics, Vol. 57, Birkhauser, Boston, 1985, page 38.
D. Shanks, Solved and Unsolved Problems in Number Theory. Chelsea, NY, 2nd edition, 1978, p. 15.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
David Wells, The Penguin Dictionary of Curious and Interesting Numbers. Penguin Books, NY, 1986, Revised edition 1987. See entry 455052511 at p. 190.

David Baugh, Table of n, a(n) for n = 0..29 (terms n = 1..27 from Charles R Greathouse IV).
Chris K. Caldwell, How Many Primes Are There?
Chris K. Caldwell, Mark Deleglise's work
Muhammed Hüsrev Cilasun, An Analytical Approach to Exponent-Restricted Multiple Counting Sequences, arXiv preprint arXiv:1412.3265 [math.NT], 2014.
Muhammed Hüsrev Cilasun, Generalized Multiple Counting Jacobsthal Sequences of Fermat Pseudoprimes, Journal of Integer Sequences, Vol. 19, 2016, #16.2.3.
Jens Franke, Thorsten Kleinjung, Jan Büthe, and Alexander Jost, A practical analytic method for calculating pi(x), Math. Comp. 86 (2017), 2889-2909.
Xavier Gourdon, a(22) found by pi(x) project
Xavier Gourdon and Pascal Sebah, The pi(x) project : results and current computations
Andrew Granville and Greg Martin, Prime number races, Amer. Math. Monthly, 113 (No. 1, 2006), 1-33.
Andrew Granville and Greg Martin, Prime number races, arXiv:math/0408319 [math.NT], 2004.
Cino Hilliard, Sum of primes [unusable link]
Ronald K. Hoeflin, Titan Test
D. S. Kluk and N. J. A. Sloane, Correspondence, 1979, [see p. 6 of the pdf].
Rishi Kumar, Kepler Sets of Second-Order Linear Recurrence Sequences Over Q_p, arXiv:2406.05890 [math.NT], 2024. See p. 7.
J. C. Lagarias, V. S. Miller, and A. M. Odlyzko, Computing pi(x): The Meissel-Lehmer method, Math. Comp., 44 (1985), pp. 537-560.
J. C. Lagarias and Andrew M. Odlyzko, Computing pi(x): An analytic method, J. Algorithms, 8 (1987), pp. 173-191.
Pieter Moree, Izabela Petrykiewicz, and Alisa Sedunova, A computational history of prime numbers and Riemann zeros, arXiv:1810.05244 [math.NT], 2018. See Table 1 p. 6.
Tomás Oliveira e Silva, Tables of values of pi(x) and of pi2(x)
Tomás Oliveira e Silva, Computing pi(x): the combinatorial method, Revista do Detua, Vol. 4, N 6, March 2006.
David J. Platt, Computing pi(x) analytically, arXiv:1203.5712 [math.NT], 2012-2013.
Vladimir Pletser, Conjecture on the value of Pi(10^26), the number of primes less than 10^26, arXiv:1307.4444 [math.NT], 2013.
Vladimir Pletser, Global Generalized Mersenne Numbers: Definition, Decomposition, and Generalized Theorems, Preprints.org, 2024. See p. 20.
Douglas B. Staple, The combinatorial algorithm for computing pi(x), arXiv:1503.01839 [math.NT], 2015.
M. R. Watkins, The distribution of prime numbers
Eric Weisstein's World of Mathematics, Prime Counting Function
Wikipedia, Prime number theorem
Robert G. Wilson v, Letter to N. J. A. Sloane, Jan. 1989
Index entries for sequences related to numbers of primes in various ranges

Cf. A000720, A006879, A006988, A007053, A011557, A025201, A040014.

a006880 = a000720 . (10 ^)  -- Reinhard Zumkeller, Mar 17 2015

Table[PrimePi[10^n], {n, 0, 14}] (* Jean-François Alcover, Nov 08 2016, corrected Sep 29 2020, a(14) being the maximum computable with certain implementations *)

a(n)=primepi(10^n) \\ Charles R Greathouse IV, Nov 08 2011

a(n) = A000720(10^n). - M. F. Hasler, Dec 03 2018

Limit_{n->oo} a(n)/a(n-1) = 10. - Stefano Spezia, Aug 31 2025

Lehmer gave the incorrect value 455052512 for the 10th term. More terms May 1996. Jud McCranie points out that the 11th term is not 4188054813 but rather 4118054813.
a(22) from Robert G. Wilson v, Sep 04 2001
a(23) (see Gourdon and Sebah) has yet to be verified and the assumed error is +-1. - Robert G. Wilson v, Jul 10 2002 [The actual error was 14037804. - N. J. A. Sloane, Nov 28 2007]
a(23) corrected by N. J. A. Sloane from the web page of Tomás Oliveira e Silva, Nov 28 2007
a(25) from J. Buethe, J. Franke, A. Jost, T. Kleinjung, Jun 01 2013, who said: "We have calculated pi(10^25) = 176846309399143769411680 unconditionally, using an analytic method based on Weil's explicit formula".
a(26) from Douglas B. Staple, Dec 02 2014
a(27) in the b-file from David Baugh and Kim Walisch via Charles R Greathouse IV, Jun 01 2016
a(28) in the b-file from David Baugh and Kim Walisch, Oct 26 2020
a(29) in the b-file from David Baugh and Kim Walisch, Feb 28 2022

A061273 Number of primes between successive powers of e (= 2.718281828...).

Original entry on oeis.org

1, 3, 4, 8, 18, 45, 104, 246, 590, 1447, 3582, 8864, 22216, 55989, 141738, 360486, 920892, 2360953, 6073160, 15664216, 40510215, 105017120, 272821646, 710143301, 1851830021, 4836984396, 12653549540, 33148606878, 86954036990, 228373959896, 600482317125, 1580587864193, 4164596465439, 10983396620288

Offset: 0

Amarnath Murthy, Apr 25 2001

nonn

			a(0) = 1 as 2 is the only between 1 and e. a(4) = 18, as there are 18 primes between e^4 = 54.59815... and e^5 = 148.4131591...

Robert G. Wilson v, Table of n, a(n) for n = 0..38

Cf. A061274.

First differences of A040014.

# To find all primes between ceiling(base^(n-1)) and floor(base^n). This uses the Maple function 'isprime', which is a probabilistic primality testing routine.
base := exp(1); maxx := 15; for n from 1 to maxx do for i from ceil(base^(n-1)) to floor(base^(n)) do if (isprime(i)) then numPrimes := numPrimes + 1: end if; od; printf("Number of primes between ceil(%f)^%d and floor(%f)^%d is %d ", base, n-1, base, n, numPrimes); od; # Winston C. Yang (winston(AT)cs.wisc.edu), May 17 2001

Differences[PrimePi[#]&/@(E^Range[0,35])] (* Harvey P. Dale, May 03 2023 *)

a(n) ~ 1/n * e^n * (e-1).

More terms from Winston C. Yang (winston(AT)cs.wisc.edu), May 17 2001

a(29)-a(33) from Robert G. Wilson v, Jun 05 2016

A105457 Number of irregular primes less than e^n.

Original entry on oeis.org

0, 0, 0, 1, 6, 21, 66, 170, 404, 984, 2384, 5877, 14459, 36720, 92657, 234376, 597082, 1525209, 3913689, 10076194, 26016985

Offset: 1

Robert G. Wilson v, Apr 07 2005

Cf. A040014, A105461, A105466.

ip={ the list of irregular primes to 12 million }; Table[ Length[ Select[ip, # < E^n &]], {n, 16}]

a(16) corrected and a(17)-a(21) added by Amiram Eldar, Mar 05 2019

A055730 Number of primes <= 5^n.

Original entry on oeis.org

0, 3, 9, 30, 114, 445, 1821, 7671, 33118, 145713, 650133, 2934858, 13375865, 61444585, 284140656, 1321453490, 6175961983, 28988040005, 136575061279, 645620925545, 3061129684411, 14552990145243, 69354801708586, 331251325552977, 1585299642009257, 7600886353341754, 36504944044424979

Offset: 0

Robert G. Wilson v, Jun 09 2000

nonn

Cf. A006880, A007053 and A040014.

Mathematica
```
Table[PrimePi[5^n], {n, 0, 19}]
```

a(n) = primepi(5^n); \\ Michel Marcus, Aug 25 2014

a(n) = A000720(A000351(n)). - Michel Marcus, Aug 25 2014

a(19) corrected by Henri Lifchitz, Nov 11 2012
a(20)-a(27) from Henri Lifchitz, Nov 11 2012
a(28)-a(32) from Henri Lifchitz, Aug 25 2014
Definition corrected by Jean-Claude Arbaut, Oct 07 2015
a(33) from Robert Price, May 07 2025

A055731 Number of primes < 6^n.

Original entry on oeis.org

0, 3, 11, 47, 210, 985, 4821, 24427, 126726, 669432, 3588148, 19453038, 106460872, 587176205, 3259873268, 18200088376, 102107048666, 575281018454, 3253321522134, 18459252891532, 105048100696856, 599403542263094, 3428437672359713, 19652744592040804, 112879982373565581, 649538196329702877, 3743885544339750283, 21612949469350359942, 124947894360104092955

Offset: 0

Robert G. Wilson v, Jun 09 2000

nonn

David Baugh, Table of n, a(n) for n = 0..33 (terms n = 29..33 found using Kim Walisch's primecount program)
Index entries for sequences related to numbers of primes in various ranges

Cf. A006880, A007053 and A040014.

Cf. A000400, A000720.

Mathematica
```
Table[PrimePi[6^n], {n, 0, 17}]
```

a(n) = primepi(6^n); \\ Michel Marcus, Oct 05 2020

a(n) = A000720(A000400(n)). - Michel Marcus, Oct 05 2020

a(18)-a(24) from Henri Lifchitz, Nov 11 2012

a(25)-a(28) from Henri Lifchitz, Aug 25 2014

A055732 Number of primes <= 7^n.

Original entry on oeis.org

0, 4, 15, 68, 357, 1939, 11098, 65685, 397764, 2453911, 15353323, 97163605, 620646217, 3995149838, 25885182840, 168650876819, 1104127111380, 7259025764932, 47901523494261, 317140339436292, 2105877503513609, 14020561559878216, 93570332318306847, 625829902867176558, 4194084944321575624, 28158446635057280702, 189368274899202732322

Offset: 0

Robert G. Wilson v, Jun 09 2000

nonn

David Baugh, Table of n, a(n) for n = 0..30 (terms n = 27..30 found using Kim Walisch's primecount program)
Index entries for sequences related to numbers of primes in various ranges

Cf. A006880, A007053 and A040014.

Mathematica
```
Table[PrimePi[7^n], {n, 0, 16}]
```

a(n) = primepi(7^n); \\ Michel Marcus, Aug 25 2014

a(n) = A000720(A000420(n)). - Michel Marcus, Aug 25 2014

a(17)-a(22) from Henri Lifchitz, Nov 11 2012

a(23)-a(26) from Henri Lifchitz, Aug 25 2014

A182564 Number of primes < Fibonacci(n).

Original entry on oeis.org

0, 0, 0, 0, 1, 2, 4, 5, 8, 11, 16, 23, 34, 50, 74, 111, 166, 250, 376, 574, 871, 1329, 2033, 3120, 4794, 7396, 11425, 17688, 27426, 42612, 66317, 103298, 161207, 251757, 393790, 616645, 966507, 1516410, 2381429, 3743010, 5888201, 9269519, 14604028, 23023555, 36322186, 57337078, 90565070, 143130478

Offset: 0

Alex Ratushnyak, May 05 2012

nonn

			Fibonacci(7)=13, there are 5 primes less than 13, so a(7)=5.

Cf. A000040, A000045, A006880, A007053, A028505, A038107, A040014.

Table[If[PrimeQ[Fibonacci[n]],PrimePi[Fibonacci[n]-1],PrimePi[ Fibonacci[ n]]],{n,0,50}] (* Harvey P. Dale, Feb 12 2022 *)

a(n) = primepi(fibonacci(n)-1) \\ Michel Marcus, May 13 2013

A229661 Rounded percentage of primes less than 10^n.

Original entry on oeis.org

0, 40, 25, 17, 12, 10, 8, 7, 6, 5, 5, 4, 4, 3, 3, 3, 3, 3, 2, 2, 2, 2, 2, 2, 2, 2

Offset: 0

Jean-François Alcover, Sep 27 2013

Please refer to the explanations and comments given in A006879 and A006880.

			There are 4 primes less than 10 (i.e., 2, 3, 5, 7), so a(1) = 40.

Cf. A000720, A006879, A006880, A007053, A040014, A006988.

a[n_] := PrimePi[10^n]/10^(n-2) // Round;
(* or *) a[n_] := A006880[[n+1]]/10^(n-2) // Round; Table[Print["10^", n, " ", a[n], "%"]; a[n], {n, 0, 25}] (* Jean-François Alcover, Sep 27 2013 *)

a(n) = pi(10^n)/10^(n-2) rounded.

cp's OEIS Frontend

A006880 Number of primes < 10^n.

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A061273 Number of primes between successive powers of e (= 2.718281828...).

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A105457 Number of irregular primes less than e^n.

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A055730 Number of primes <= 5^n.

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A055731 Number of primes < 6^n.

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A055732 Number of primes <= 7^n.

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A182564 Number of primes < Fibonacci(n).

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PARI

A229661 Rounded percentage of primes less than 10^n.

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