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 1-4 of 4 results.

A246852 Numbers n such that sigma(n+2) - sigma(n) = n + 2.

Original entry on oeis.org

1, 2, 22, 14926, 31048, 69106, 246262, 5860168, 307164670, 881198662, 1489455646, 2386555630, 8225563702, 14311679062, 111494234182, 154357775302, 299004519622, 870455062822, 970388922262, 991817878342, 1677028870822, 1782783762502, 1830446935222
Offset: 1

Views

Author

Jaroslav Krizek, Sep 05 2014

Keywords

Comments

Also numbers n such that A001065(n+2) = A000203(n). - Michel Marcus, Sep 06 2014

Examples

			Number 22 is in sequence because sigma(22+2) - sigma(22) = 60 - 36 = 24 = 22 + 2.

Links

Crossrefs

Cf. A000203, A067816, A246851, A246853, A246854, A246855.

Programs

  • Magma
    [n:n in[1..10^7] | SumOfDivisors(n+2)-SumOfDivisors(n) eq n+2]
  • Mathematica
    Select[Range[6*10^6], DivisorSigma[1, # + 2] - DivisorSigma[1, #] == # + 2 &] (* Jake L Lande, Jun 30 2024 *)
  • PARI
    for(n=1,10^7,if(sigma(n+2)-sigma(n)==n+2,print1(n,", "))) \\ Derek Orr, Sep 05 2014

Extensions

a(9)-a(14) from Hiroaki Yamanouchi, Sep 10 2014
a(15)-a(23) from Giovanni Resta, Jul 13 2015

A246853 Numbers n such that sigma(n+3) - sigma(n) = n + 3.

Original entry on oeis.org

7, 6285, 4693485, 54028959, 75898473, 724416741, 2359059709, 4901493769, 321212249593, 511578306649, 534245763769, 6158645822473
Offset: 1

Views

Author

Jaroslav Krizek, Sep 05 2014

Keywords

Comments

Also numbers n such that A001065(n+3) = A000203(n). - Michel Marcus, Sep 06 2014
a(13) > 10^13. - Giovanni Resta, Jul 13 2015

Examples

			Number 7 is in sequence because sigma(7+3) - sigma(7) = 18 - 8 = 10 = 7 + 3.

Crossrefs

Cf. A000203, A067816, A246851, A246852, A246854, A246855.

Programs

  • Magma
    [n:n in[1..10^7] | SumOfDivisors(n+3)-SumOfDivisors(n) eq n+3]
  • PARI
    for(n=1,10^7,if(sigma(n+3)-sigma(n)==n+3,print1(n,", "))) \\ Derek Orr, Sep 05 2014

Extensions

a(4)-a(8) from Hiroaki Yamanouchi, Sep 10 2014
a(9)-a(12) from Giovanni Resta, Jul 13 2015

A246854 Numbers n such that sigma(n+4) - sigma(n) = n + 4.

Original entry on oeis.org

1, 4, 26, 122, 146, 458, 746, 3746, 47612, 16065500, 388978292, 5313509288, 64278616556
Offset: 1

Views

Author

Jaroslav Krizek, Sep 05 2014

Keywords

Comments

Also numbers n such that A001065(n+4) = A000203(n). - Michel Marcus, Sep 06 2014
a(14) (if it exists) > 10^11. - Hiroaki Yamanouchi, Sep 10 2014
a(14) (if it exists) > 10^13. - Giovanni Resta, Jul 13 2015

Examples

			Number 26 is in sequence because sigma(26+4) - sigma(26) = 72 - 42 = 30 = 26 + 4.

Crossrefs

Cf. A000203, A067816, A246851, A246852, A246853, A246855.

Programs

  • Magma
    [n:n in[1..10^7] | SumOfDivisors(n+4)-SumOfDivisors(n) eq n+4]
  • PARI
    for(n=1,10^7,if(sigma(n+4)-sigma(n)==n+4,print1(n,", "))) \\ Derek Orr, Sep 05 2014

Extensions

a(10)-a(13) from Hiroaki Yamanouchi, Sep 10 2014

A246855 Numbers k such that sigma(k+5) - sigma(k) = k + 5.

Original entry on oeis.org

3577, 14773, 2843579
Offset: 1

Views

Author

Jaroslav Krizek, Sep 05 2014

Keywords

Comments

Also numbers k such that A001065(k+5) = A000203(k). - Michel Marcus, Sep 06 2014
a(4) (if it exists) > 10^11. - Hiroaki Yamanouchi, Sep 10 2014
a(4) (if it exists) > 10^13. - Giovanni Resta, Jul 13 2015
No other terms < 2.7*10^15. - Jud McCranie, Jul 27 2025

Examples

			Number 3577 is in sequence because sigma(3577+5) - sigma(3577) = 7800 - 4218 = 3582 = 3577 + 5.

Crossrefs

Cf. A000203, A067816, A246851, A246852, A246853, A246854.

Programs

  • Magma
    [n:n in[1..10^7] | SumOfDivisors(n+5)-SumOfDivisors(n) eq n+5];
  • Mathematica
    Select[Range[285*10^4],DivisorSigma[1,#+5]-DivisorSigma[1,#]==#+5&] (* Harvey P. Dale, Jun 21 2024 *)
  • PARI
    for(n=1,10^7,if(sigma(n+5)-sigma(n)==n+5,print1(n,", "))) \\ Derek Orr, Sep 05 2014
Showing 1-4 of 4 results.

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

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