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 1-3 of 3 results.

A295996 One quarter of number of Gaussian primes whose norm is 4*n+1 or less.

Original entry on oeis.org

0, 3, 4, 6, 8, 8, 8, 10, 10, 12, 14, 14, 15, 17, 17, 19, 19, 19, 21, 21, 21, 21, 23, 23, 25, 27, 27, 29, 31, 31, 32, 32, 32, 32, 34, 34, 34, 36, 36, 38, 38, 38, 38, 40, 40, 42, 42, 42, 44, 46, 46, 46, 46, 46, 46, 46, 46, 48, 50, 50, 52, 52, 52, 52, 54, 54, 54, 56
Offset: 0

Views

Author

Seiichi Manyama, Dec 02 2017

Keywords

Examples

			The Gaussian primes whose norm is 9 or less;
      *        3i,
    *   *      -1+2i, 1+2i
  * *   * *    -2+i, -1+i, 1+i, 2+i
*           *  -3, 3
  * *   * *    -2-i, -1-i, 1-i, 2-i
    *   *      -1-2i, 1-2i
      *        -3i
               a(2) = 16/4 = 4.
		

Crossrefs

Programs

  • 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
    def A295996(n)
      ary1 = A(1, n)
      ary3 = A(3, Math.sqrt(n).to_i) + [0]
      [0] + (1..n).map{|i| 1 + 2 * ary1[i] + ary3[(Math.sqrt(4 * i + 1).to_i - 3) / 4]}
    end
    p A295996(100)

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
Showing 1-3 of 3 results.