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 1-5 of 5 results.

A015858 Numbers k such that phi(k) | sigma(k + 11).

Original entry on oeis.org

1, 2, 3, 4, 6, 8, 9, 10, 12, 13, 16, 18, 19, 20, 24, 35, 36, 45, 49, 51, 74, 77, 79, 84, 91, 104, 108, 113, 124, 129, 130, 144, 148, 180, 198, 219, 224, 279, 286, 308, 380, 407, 434, 435, 459, 490, 584, 609, 610, 616, 624, 627, 628, 640, 644, 679, 779
Offset: 1

Views

Author

Robert G. Wilson v

Keywords

Links

Crossrefs

Cf. A015834 (m=1), A015837 (m=2), A015840 (m=3), A015841 (m=4), A015843 (m=5), A015844 (m=6), A015845 (m=7), A015851 (m=8), A015853 (m=9), A015856 (m=10), this sequence (m=11), A015859 (m=12), A015860 (m=13).

Programs

  • Magma
    [n: n in [1..900] | DivisorSigma(1,n+11) mod EulerPhi(n) eq 0]; // G. C. Greubel, Dec 13 2018
  • Mathematica
    Select[Range[800],Divisible[DivisorSigma[1,#+11],EulerPhi[#]]&] (* Harvey P. Dale, Aug 01 2016 *)
  • PARI
    is(n)=!(sigma(n+11)%eulerphi(n)) \\ Charles R Greathouse IV, Sep 25 2012

Extensions

Missing a(1)=1 inserted by Sean A. Irvine, Dec 13 2018

A015859 Numbers k such that phi(k) | sigma(k + 12).

Original entry on oeis.org

1, 2, 3, 10, 12, 14, 15, 16, 18, 21, 26, 30, 35, 39, 42, 44, 54, 65, 75, 76, 90, 108, 123, 126, 153, 156, 165, 218, 234, 252, 270, 364, 366, 370, 396, 462, 474, 494, 508, 525, 540, 558, 615, 620, 630, 646, 702, 732, 814, 852, 858, 918, 980, 1022, 1044
Offset: 1

Views

Author

Robert G. Wilson v

Keywords

Links

Crossrefs

Cf. A015834 (m=1), A015837 (m=2), A015840 (m=3), A015841 (m=4), A015843 (m=5), A015844 (m=6), A015845 (m=7), A015851 (m=8), A015853 (m=9), A015856 (m=10), A015858 (m=11), this sequence (m=12), A015860 (m=13).

Programs

  • Magma
    [n: n in [1..900] | DivisorSigma(1,n+12) mod EulerPhi(n) eq 0]; // G. C. Greubel, Dec 13 2018
  • Mathematica
    Select[Range[1100],Divisible[DivisorSigma[1,#+12],EulerPhi[#]]&] (* Harvey P. Dale, Jun 01 2018 *)
  • PARI
    is(n)=!(sigma(n+12)%eulerphi(n)) \\ Charles R Greathouse IV, Sep 25 2012

Extensions

Missing a(1)=1 inserted by Sean A. Irvine, Dec 13 2018

A015860 Numbers k such that phi(k) | sigma(k + 13).

Original entry on oeis.org

1, 2, 4, 6, 7, 8, 9, 10, 11, 15, 20, 25, 27, 34, 38, 41, 42, 44, 56, 57, 64, 66, 80, 82, 120, 122, 128, 146, 152, 155, 164, 176, 204, 222, 237, 310, 330, 331, 342, 377, 378, 400, 427, 460, 465, 490, 500, 504, 560, 602, 610, 626, 704, 722, 770, 817, 861
Offset: 1

Views

Author

Robert G. Wilson v

Keywords

Links

Crossrefs

Cf. A015834 (m=1), A015837 (m=2), A015840 (m=3), A015841 (m=4), A015843 (m=5), A015844 (m=6), A015845 (m=7), A015851 (m=8), A015853 (m=9), A015856 (m=10), A015858 (m=11), A015859 (m=12), this sequence (m=13).

Programs

  • Magma
    [n: n in [1..900] | DivisorSigma(1,n+13) mod EulerPhi(n) eq 0]; // G. C. Greubel, Dec 13 2018
  • Mathematica
    Select[Range[900], Mod[DivisorSigma[1, #+13], EulerPhi[#]]==0 &] (* G. C. Greubel, Dec 13 2018 *)
  • PARI
    is(n)=!(sigma(n+13)%eulerphi(n)) \\ Charles R Greathouse IV, Sep 25 2012

Extensions

Missing a(1)=1 inserted by Sean A. Irvine, Dec 13 2018

A015853 Numbers k such that phi(k) | sigma(k + 9).

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 10, 12, 13, 14, 21, 24, 26, 30, 31, 37, 42, 45, 48, 50, 57, 60, 68, 76, 78, 96, 105, 111, 133, 156, 168, 175, 181, 196, 200, 215, 273, 286, 288, 290, 310, 320, 336, 350, 361, 369, 381, 399, 406, 420, 450, 465, 543, 585, 600, 612, 656, 740
Offset: 1

Views

Author

Robert G. Wilson v

Keywords

Links

Crossrefs

Cf. A015834 (m=1), A015837 (m=2), A015840 (m=3), A015841 (m=4), A015843 (m=5), A015844 (m=6), A015845 (m=7), A015851 (m=8), this sequence (m=9), A015856 (m=10), A015858 (m=11), A015859 (m=12), A015860 (m=13).

Programs

  • Magma
    [n: n in [1..900] | DivisorSigma(1,n+9) mod EulerPhi(n) eq 0]; // G. C. Greubel, Dec 13 2018
  • Mathematica
    Select[Range[1000], Divisible[DivisorSigma[1,#+9], EulerPhi[#]] &] (* Amiram Eldar, Dec 13 2018 *)
  • PARI
    is(n)=!(sigma(n+9)%eulerphi(n)) \\ Charles R Greathouse IV, Sep 25 2012

Extensions

Missing a(1)=1 inserted by Sean A. Irvine, Dec 13 2018

A015856 Numbers k such that phi(k) | sigma(k + 10).

Original entry on oeis.org

1, 2, 3, 4, 5, 7, 12, 13, 14, 20, 28, 29, 32, 36, 44, 45, 52, 53, 56, 60, 66, 77, 84, 86, 104, 105, 108, 110, 123, 130, 144, 172, 221, 228, 238, 270, 287, 312, 342, 366, 380, 385, 396, 441, 468, 558, 584, 585, 588, 644, 672, 750, 754, 760, 854, 864
Offset: 1

Views

Author

Robert G. Wilson v

Keywords

Links

Crossrefs

Cf. A015834 (m=1), A015837 (m=2), A015840 (m=3), A015841 (m=4), A015843 (m=5), A015844 (m=6), A015845 (m=7), A015851 (m=8), A015853 (m=9), this sequence (m=10), A015858 (m=11), A015859 (m=12), A015860 (m=13).

Programs

  • Magma
    [n: n in [1..900] | DivisorSigma(1,n+10) mod EulerPhi(n) eq 0]; // G. C. Greubel, Dec 13 2018
  • Mathematica
    Select[Range[1000], Divisible[DivisorSigma[1,#+10], EulerPhi[#]] &] (* Amiram Eldar, Dec 13 2018 *)
  • PARI
    is(n)=!(sigma(n+10)%eulerphi(n)) \\ Charles R Greathouse IV, Sep 25 2012

Extensions

Missing a(1)=1 inserted by Sean A. Irvine, Dec 13 2018
Showing 1-5 of 5 results.

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

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