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.

A232703 Numbers k that divide sigma(k) + sigma(k^2).

Original entry on oeis.org

1, 2, 185, 113125, 535350201, 71373089217, 82225037115, 156231750533, 268821356379
Offset: 1

Views

Author

Alex Ratushnyak, Nov 28 2013

Keywords

Comments

a(10) > 10^12. - Giovanni Resta, Jun 10 2016

Crossrefs

Cf. A000203 (sigma(n) = sum of divisors of n).
Cf. A232547, A065764, A247222.

Programs

  • Mathematica
    Select[Range[150000], Mod[Plus @@ DivisorSigma[1, {#, #^2}], #] == 0 &] (* Giovanni Resta, Jun 10 2016 *)

Extensions

a(6)-a(9) from Giovanni Resta, Jun 10 2016

A232547 Numbers n such that sigma(n^2) mod sigma(n) = n.

Original entry on oeis.org

7581, 988893, 1658073, 468539757, 35124206517
Offset: 1

Views

Author

Alex Ratushnyak, Nov 25 2013

Keywords

Comments

a(6) > 10^12. - Giovanni Resta, Jun 10 2016

Crossrefs

Cf. A000203 (sigma(n) = sum of divisors of n), A065764, A232703, A247222.

Extensions

a(5) from Giovanni Resta, Jun 10 2016
Showing 1-2 of 2 results.

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

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