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.

Previous Showing 11-14 of 14 results.

A125871 Numbers k such that p=14*k+1 is prime and cos(2*Pi/p) is an algebraic number of a 7-smooth degree, but not 5-smooth.

Original entry on oeis.org

2, 3, 5, 8, 9, 14, 15, 20, 24, 27, 30, 32, 35, 45, 48, 50, 54, 63, 72, 75, 98, 105, 144, 162, 180, 189, 192, 200, 224, 240, 252, 300, 320, 420, 450, 500, 504, 525, 540, 560, 588, 630, 750, 768, 864, 875, 900, 960, 980, 1029, 1080, 1134, 1215, 1280, 1323
Offset: 1

Views

Author

Artur Jasinski, Dec 13 2006

Keywords

Comments

Numbers k such that p=14*k+1 is prime and the greatest prime divisor of p-1 is 7.

Crossrefs

Cf. A125866-A125878.

Programs

  • Mathematica
    Do[If[Take[FactorInteger[EulerPhi[14n+1]][[ -1]],1]=={7} && PrimeQ[14n+1],Print[n]],{n,1,10000}]

Extensions

Edited by Don Reble, Apr 24 2007

A125872 Odd numbers k such that cos(2*Pi/k) is an algebraic number of an 11-smooth degree, but not 7-smooth.

Original entry on oeis.org

23, 67, 69, 89, 115, 121, 161, 199, 201, 207, 253, 267, 299, 331, 335, 345, 353, 363, 391, 397, 437, 445, 463, 469, 483, 575, 597, 603, 605, 617, 621, 623, 661, 667, 713, 727, 737, 759, 801, 805, 847, 851, 871, 881, 897, 943, 979, 989, 991, 993, 995, 1005
Offset: 1

Views

Author

Artur Jasinski, Dec 13 2006

Keywords

Comments

A regular polygon of a(n) sides can be constructed if one also has an angle trisector, 5-sector, 7-sector and 11-sector.

Crossrefs

Cf. A125866-A125878.

Programs

  • Mathematica
    Do[If[Take[FactorInteger[EulerPhi[2n+1]][[ -1]],1]=={11},Print[2n+1]],{n,10000}]

Extensions

Edited by Don Reble, Apr 24 2007

A125873 Prime numbers n such that cos(2pi/n) is an algebraic number of an 11-smooth degree, but not 7-smooth.

Original entry on oeis.org

23, 67, 89, 199, 331, 353, 397, 463, 617, 661, 727, 881, 991, 1321, 1409, 1453, 1783, 2113, 2179, 2311, 2377, 2663, 2971, 3169, 3301, 3389, 3631, 3697, 3851, 4159, 4357, 4621, 4951, 5281, 5347, 5501, 6337, 6469, 7129, 7393, 7547, 8317, 8713
Offset: 1

Views

Author

Artur Jasinski, Dec 13 2006

Keywords

Crossrefs

Cf. A125866-A125878.

Programs

  • Mathematica
    Do[If[Take[FactorInteger[EulerPhi[2n+1]][[ -1]],1]=={11} && PrimeQ[2n+1],Print[2n+1]],{n,1,10000}] (*Artur Jasinski*)

Extensions

Edited by Don Reble, Apr 24 2007

A125876 Prime numbers n such that cos(2pi/n) is an algebraic number of a 13-smooth degree, but not 11-smooth.

Original entry on oeis.org

53, 79, 131, 157, 313, 521, 547, 677, 859, 911, 937, 1093, 1171, 1249, 1301, 1873, 1951, 2003, 2029, 2081, 2341, 2549, 2731, 2861, 3121, 3251, 3329, 3433, 3511, 3719, 3823, 4057, 4733, 4993, 5851, 6007, 6553, 6761, 7151, 7489, 7723, 8009
Offset: 1

Views

Author

Artur Jasinski, Dec 13 2006

Keywords

Crossrefs

Cf. A125866-A125878.

Programs

  • Mathematica
    Do[If[Take[FactorInteger[EulerPhi[2n+1]][[ -1]],1]=={13} && PrimeQ[2n+1],Print[2n+1]],{n,1,10000}] (*Artur Jasinski*)

Extensions

Edited by Don Reble, Apr 24 2007
Previous Showing 11-14 of 14 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.