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.

A078908 Let r+i*s be the sum, with multiplicity, of the first-quadrant Gaussian primes dividing n; sequence gives r values (with a(1) = 0).

Original entry on oeis.org

0, 2, 3, 4, 3, 5, 7, 6, 6, 5, 11, 7, 5, 9, 6, 8, 5, 8, 19, 7, 10, 13, 23, 9, 6, 7, 9, 11, 7, 8, 31, 10, 14, 7, 10, 10, 7, 21, 8, 9, 9, 12, 43, 15, 9, 25, 47, 11, 14, 8, 8, 9, 9, 11, 14, 13, 22, 9, 59, 10, 11, 33, 13, 12, 8, 16, 67, 9, 26, 12, 71, 12, 11, 9, 9, 23, 18, 10, 79, 11, 12, 11
Offset: 1

Views

Author

N. J. A. Sloane, Jan 11 2003

Keywords

Comments

A Gaussian integer z = x+iy is in the first quadrant if x > 0, y >= 0. Just one of the 4 associates z, -z, i*z, -i*z is in the first quadrant.
The sequence is fully additive.

Examples

			5 factors into the product of the primes 1+2*i, 1-2*i, but the first-quadrant associate of 1-2*i is i*(1-2*i) = 2+i, so r+i*s = 1+2*i + 2+i = 3+3*i. Therefore a(5) = 3.

Links

Crossrefs

Cf. A078458, A078909, A078910, A078911, A080088, A080089.

Programs

  • Mathematica
    a[n_] := Module[{f = FactorInteger[n, GaussianIntegers->True]}, p = f[[;;,1]]; e = f[[;;,2]]; Re[Plus @@ ((If[Abs[#] == 1, 0, #]& /@ p) * e)]]; Array[a, 100] (* Amiram Eldar, Feb 28 2020 *)

Extensions

More terms and information from Vladeta Jovovic, Jan 27 2003

A078909 Let r+i*s be the sum, with multiplicity, of the first-quadrant Gaussian primes dividing n; sequence gives s values.

Original entry on oeis.org

0, 2, 0, 4, 3, 2, 0, 6, 0, 5, 0, 4, 5, 2, 3, 8, 5, 2, 0, 7, 0, 2, 0, 6, 6, 7, 0, 4, 7, 5, 0, 10, 0, 7, 3, 4, 7, 2, 5, 9, 9, 2, 0, 4, 3, 2, 0, 8, 0, 8, 5, 9, 9, 2, 3, 6, 0, 9, 0, 7, 11, 2, 0, 12, 8, 2, 0, 9, 0, 5, 0, 6, 11, 9, 6, 4, 0, 7, 0, 11, 0, 11, 0, 4, 8, 2, 7, 6, 13, 5, 5, 4, 0, 2, 3, 10, 13, 2, 0
Offset: 1

Views

Author

N. J. A. Sloane, Jan 11 2003

Keywords

Comments

A Gaussian integer z = x+iy is in the first quadrant if x > 0, y >= 0. Just one of the 4 associates z, -z, i*z, -i*z is in the first quadrant.
The sequence is fully additive.

Examples

			5 factors into the product of the primes 1+2*i, 1-2*i, but the first-quadrant associate of 1-2*i is i*(1-2*i) = 2+i, so r+i*s = 1+2*i + 2+i = 3+3*i. Therefore a(5) = 3.

Links

Crossrefs

Cf. A078458, A078908, A078910, A078911, A080088, A080089.

Programs

  • Mathematica
    a[n_] := Module[{f = FactorInteger[n, GaussianIntegers->True]}, p = f[[;;,1]]; e = f[[;;,2]]; Im[Plus @@ ((If[Abs[#] == 1, 0, #]& /@ p) * e)]]; Array[a, 100] (* Amiram Eldar, Feb 28 2020 *)

Extensions

More terms and further information from Vladeta Jovovic, Jan 27 2003

A080089 Let r+i*s be the sum of the first-quadrant Gaussian primes dividing prime(n); sequence gives s values.

Original entry on oeis.org

2, 0, 3, 0, 0, 5, 5, 0, 0, 7, 0, 7, 9, 0, 0, 9, 0, 11, 0, 0, 11, 0, 0, 13, 13, 11, 0, 0, 13, 15, 0, 0, 15, 0, 17, 0, 17, 0, 0, 15, 0, 19, 0, 19, 15, 0, 0, 0, 0, 17, 21, 0, 19, 0, 17, 0, 23, 0, 23, 21, 0, 19, 0, 0, 25, 25, 0, 25, 0, 23, 25, 0, 0, 25, 0, 0, 27, 25, 21, 23, 0, 29, 0, 29, 0, 0, 27, 25
Offset: 1

Views

Author

Vladeta Jovovic, Jan 27 2003

Keywords

Links

Crossrefs

Cf. A078908, A078909, A080088.

Programs

  • Mathematica
    s[n_] := Module[{f = FactorInteger[n, GaussianIntegers->True]}, p = f[[;;,1]]; e = f[[;;,2]]; Im[Plus @@ ((If[Abs[#]==1, 0, #]& /@ p) * e)]]; s /@ Select[ Range[100], PrimeQ] (* Amiram Eldar, Feb 28 2020 *)
Showing 1-3 of 3 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement.