cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-10 of 10 results.

A091098 Number of primes of the form 4k+1 less than 10^n.

Original entry on oeis.org

1, 11, 80, 609, 4783, 39175, 332180, 2880504, 25423491, 227523275, 2059020280, 18803924340, 173032709183, 1602470783672, 14922284735484, 139619168787795, 1311778575685086, 12369977142579584, 117028833597800689, 1110409801150582707
Offset: 1

Views

Author

T. D. Noe, Dec 19 2003

Keywords

Crossrefs

Cf. A091099 (number of primes of the form 4k+3 less than 10^n).

Programs

  • Mathematica
    cnt=0; k=0; Table[lim=10^n; While[4k+1
    				

Extensions

a(10)-a(16) from Robert G. Wilson v, Dec 22 2003
a(17)-a(20) from Marc Deleglise, Jun 28 2007

A091295 (Number of primes == 3 mod 4 less than 10^n) - (number of primes == 1 mod 4 less than 10^n).

Original entry on oeis.org

1, 2, 7, 10, 25, 147, 218, 446, 551, 5960, 14252, 63337, 118472, 183457, 951700, 3458334, 6284060, 2581691, 80743228, 259753425
Offset: 1

Views

Author

Enoch Haga, Feb 23 2004

Keywords

Examples

			a(1) = 1 because below 10^1 3 and 7 are 3 mod 4 and 5 is 1 mod 4 and the difference is 2-1=1.
		

References

  • Hans Riesel, Prime Numbers and Computer Methods for Factorization, 2nd ed., Birkhauser, The distribution of primes between the two series 4n+1 and 4n+3, pages 73-77, with graphs.

Crossrefs

Formula

a(n) = A091099(n) - A091098(n) = A093153(n) + 1. [Max Alekseyev, May 17 2009]

Extensions

a(17)-a(20) from Marc Deleglise, Jun 28 2007

A296020 Number of primes of the form 4*k+3 <= 4*n+3.

Original entry on oeis.org

1, 2, 3, 3, 4, 5, 5, 6, 6, 6, 7, 8, 8, 8, 9, 9, 10, 11, 11, 12, 13, 13, 13, 13, 13, 14, 15, 15, 15, 15, 15, 16, 17, 17, 18, 18, 18, 19, 19, 19, 20, 21, 21, 21, 22, 22, 22, 23, 23, 24, 24, 24, 25, 25, 25, 26, 27, 27, 27, 28, 28, 28, 29, 29, 29, 30, 30, 31, 31, 31
Offset: 0

Views

Author

Seiichi Manyama, Dec 02 2017

Keywords

Crossrefs

Programs

  • Mathematica
    Module[{nn=300,pr3},pr3=Table[If[PrimeQ[k]&&Mod[k,4]==3,1,0],{k,0,nn}];Table[Total[Take[pr3,4n+3]],{n,(nn-3)/4}]] (* Harvey P. Dale, Aug 10 2019 *)
  • Ruby
    require 'prime'
    def A(k, n)
      ary = []
      cnt = 0
      k.step(4 * n + k, 4){|i|
        cnt += 1 if i.prime?
        ary << cnt
      }
      ary
    end
    p A(3, 100)

A091100 Number of Gaussian primes whose norm is less than 10^n.

Original entry on oeis.org

16, 100, 668, 4928, 38404, 313752, 2658344, 23046512, 203394764, 1820205436, 16472216912, 150431552012, 1384262129028, 12819767598972, 119378281788240, 1116953361826164
Offset: 1

Views

Author

T. D. Noe, Dec 19 2003

Keywords

Crossrefs

Cf. A091098 (number of primes of the form 4k+1 less than 10^n), A091099 (number of primes of the form 4k+3 less than 10^n), A091101, A091102.
Cf. A091134 (number of Gaussian primes whose modulus is less than 10^n).

Programs

  • Mathematica
    Table[lim2=10^n; lim1=Floor[Sqrt[lim2]]; cnt=0; Do[If[x^2+y^2True], cnt++ ], {x, -lim1, lim1}, {y, -lim1, lim1}]; cnt, {n, 6}]

Formula

a(2n) = 8*A091098(2n) + 4*A091099(n) + 4.
a(n) ~ 4 Li(10^n) ~ k/n * 10^n, where k = 4/log(10) = 1.737.... - Charles R Greathouse IV, Oct 24 2012

Extensions

a(10)-a(16) from Seiichi Manyama using the data in A091098, Dec 03 2017

A091102 Number of first half-quadrant Gaussian primes whose norm is less than 10^n.

Original entry on oeis.org

3, 14, 87, 623, 4818, 39263, 332406, 2881124, 25425200, 227528084
Offset: 1

Views

Author

T. D. Noe, Dec 19 2003

Keywords

Crossrefs

Cf. A091098 (number of primes of the form 4k+1 less than 10^n), A091099 (number of primes of the form 4k+3 less than 10^n), A091101, A091102.

Programs

  • Mathematica
    Table[lim2=10^n; lim1=Floor[Sqrt[lim2]]; cnt=0; Do[If[x^2+y^2True], cnt++ ], {x, 0, lim1}, {y, 0, x}]; cnt, {n, 6}]

Formula

a(2n) = A091098(2n) + A091099(n) + 1

Extensions

a(10) calculated from the data at A091098 and A091099 by Amiram Eldar, Feb 28 2020

A093153 Difference between counts of odd composites in A093151 and A093152 [Count (1 mod 4) - count (3 mod 4)].

Original entry on oeis.org

0, 1, 6, 9, 24, 146, 217, 445, 550, 5959, 14251, 63336, 118471, 183456, 951699, 3458333, 6284059, 2581690, 80743227, 259753424
Offset: 1

Views

Author

Enoch Haga, Mar 24 2004

Keywords

Comments

In A091295 the counts are 1 higher. I computed the differences through 10^8 and the rest by extrapolating from A091098 and A091099. In the ranges given, the counts of odd composites less than 10^n are higher 1 mod 4 than 3 mod 4. They are exactly opposite for the primes less than 10^n where 3 mod 4 is higher.

Examples

			Below 10^3 there are 169 odd composites 1 mod 4 and 163 odd composites 3 mod 4, so a(3)=169-163=6
		

Crossrefs

Formula

Subtract count of odd composites 3 mod 4 less than 10^n from those 1 mod 4
a(n) = A093151(n) - A093152(n). For n>1, a(n) = A091099(n) - A091098(n) - 1. [From Max Alekseyev, May 17 2009]

Extensions

More terms from Max Alekseyev, May 17 2009

A091101 Number of first-quadrant Gaussian primes whose norm is less than 10^n.

Original entry on oeis.org

5, 27, 173, 1245, 9635, 78525, 664811, 5762247, 50850399, 455056167
Offset: 1

Views

Author

T. D. Noe, Dec 19 2003

Keywords

Crossrefs

Cf. A091098 (number of primes of the form 4k+1 less than 10^n), A091099 (number of primes of the form 4k+3 less than 10^n), A091100, A091102.

Programs

  • Mathematica
    Table[lim2=10^n; lim1=Floor[Sqrt[lim2]]; cnt=0; Do[If[x^2+y^2True], cnt++ ], {x, 0, lim1}, {y, 0, lim1}]; cnt, {n, 6}]

Formula

a(2n) = 2*A091098(2n) + 2*A091099(n) + 1.

Extensions

a(10) calculated from the data at A091098 and A091099 by Amiram Eldar, Feb 28 2020

A091134 Number of Gaussian primes a+b*i such that sqrt(a^2 + b^2) <= 10^n.

Original entry on oeis.org

100, 4928, 313752, 23046512, 1820205436, 150431552012, 12819767598972, 1116953361826164, 98959817242332844, 8883278410114778600
Offset: 1

Views

Author

Eric W. Weisstein, Dec 19 2003

Keywords

Crossrefs

Bisection of A091100.

Formula

a(n) = 8*A091098(2*n) + 4*A091099(n) + 4. - Seiichi Manyama, Dec 03 2017

Extensions

a(5)-a(10) from Seiichi Manyama using the data in A091098 and A091099, Dec 03 2017

A093151 Number of odd composites 1 mod 4 less than 10^n.

Original entry on oeis.org

1, 13, 169, 1890, 20216, 210824, 2167819, 22119495, 224576508, 2272476724, 22940979719, 231196075659, 2326967290816, 23397529216327, 235077715264515, 2360380831212204, 23688221424314913, 237630022857420415, 2382971166402199310, 23889590198849417292
Offset: 1

Views

Author

Enoch Haga, Mar 24 2004

Keywords

Examples

			Below 10^2 there are 13 odd composites so a(2)=13
		

Crossrefs

Formula

Count odd composites 1 mod 4 less than 10^n
For n>1, a(n) = 25*10^(n-2) - 1 - A091098(n). - Max Alekseyev, May 30 2007

Extensions

More terms from Max Alekseyev, May 30 2007
Extended by Max Alekseyev, Oct 13 2009

A093152 Number of odd composites below 10^n that are congruent to 3 modulo 4.

Original entry on oeis.org

0, 12, 163, 1881, 20192, 210678, 2167602, 22119050, 224575958, 2272470765, 22940965468, 231196012323, 2326967172345, 23397529032871, 235077714312816, 2360380827753871, 23688221418030854, 237630022854838725, 2382971166321456083, 23889590198589663868
Offset: 1

Views

Author

Enoch Haga, Mar 24 2004

Keywords

Examples

			Below 10^2 there are 12 odd composites 3 mod 4 so a(2)=12
		

Crossrefs

Formula

For n>1, a(n) = 25*10^(n-2) - A091099(n) [From Max Alekseyev, May 17 2009]

Extensions

a(9) from Ryan Propper, Jun 21 2005
a(10)-a(20) from Max Alekseyev, May 17 2009, Oct 08 2013
Showing 1-10 of 10 results.