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 1-2 of 2 results.

A330412 Integers m such that sigma(m) + sigma(8*m) = 18*m.

Original entry on oeis.org

34, 568, 147328, 603971584, 9663643648, 39582416502784, 696341272098017608537735168, 765635325572111542783369494684623699968, 3615610599582728119969414707766982030374842621310535527825408, 3791242500068058721125048996612134914443116117566314438843154038784
Offset: 1

Views

Author

Jinyuan Wang, Feb 12 2020

Keywords

Comments

This is the case h = 8 of the h-perfect numbers as defined in the Harborth link.

Examples

			34 is a term since sigma(34) + sigma(8*34) = 612, that is 18*34.

Links

Crossrefs

Cf. A000203, A000396, A002236, A050524, A136539, A281993, A330413.

Programs

  • PARI
    isok(m) = sigma(m) + sigma(8*m) == 18*m;

Formula

a(n) = 2^A002236(n) * A050524(n).

A334128 Integers m such that sigma(m) + sigma(7*m) = 16*m.

Original entry on oeis.org

135, 1365, 42819777
Offset: 1

Views

Author

Jinyuan Wang, May 15 2020

Keywords

Comments

This is the case h = 7 of the h-perfect numbers as defined in the Harborth link.
If gcd(m, 7) = 1 and m is even, then m must be of the form 2*q, where 27*sigma(q) = 32*q and gcd(q, 7) = 1.
a(4) > 3.5*10^12, if it exists. - Giovanni Resta, May 17 2020

Links

Crossrefs

Cf. A000203, A000396, A281993, A330412, A330413.

Programs

  • PARI
    isok(m) = sigma(m) + sigma(7*m) == 16*m;
Showing 1-2 of 2 results.

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

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