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.

A344731 Numbers k such that k divides A306069(k).

Original entry on oeis.org

1, 275, 277, 3337, 3353, 3359, 39675, 39689, 472467, 797806459, 9501109507
Offset: 1

Views

Author

Amiram Eldar, May 27 2021

Keywords

Comments

The corresponding quotients A306069(k)/k are 1, 5, 5, 7, 7, 7, 9, 9, 11, 17, 19, ...
a(12) > 7.5*10^10, if it exists.

Examples

			a(1) = 1 since A306069(1) = 1 is divisible by 1.
a(2) = 275 since A306069(275) = 1375 = 5 * 275 is divisible by 275.

Crossrefs

Cf. A286324, A306069.
The bi-unitary version of A050226.
Similar sequences: A064610, A344732, A344733.

Programs

  • Mathematica
    f[p_, e_] := If[Mod[e, 2] == 1, (e + 1), e]; s[1] = 1; s[n_] := s[n] = s[n - 1] + Times @@ f @@@ FactorInteger[n]; Select[Range[40000], Divisible[s[#], #] &]

A344733 Numbers k such that k divides A327573(k).

Original entry on oeis.org

1, 25, 387, 6063, 1416379, 1416403, 1416411, 331362359, 5068450527
Offset: 1

Views

Author

Amiram Eldar, May 27 2021

Keywords

Comments

The corresponding quotients A327573(k)/k are 1, 3, 5, 7, 11, 11, 11, 15, 17, ...
a(10) > 7.5*10^10, if it exists.

Examples

			a(1) = 1 since A327573(1) = 1 is divisible by 1.
a(2) = 25 since A327573(25) = 75 = 3 * 25 is divisible by 25.

Crossrefs

Cf. A037445, A327573.
The infinitary version of A050226.
Similar sequences: A064610, A344731, A344732.

Programs

  • Mathematica
    f[p_, e_] := 2^DigitCount[e, 2, 1]; s[1] = 1; s[n_] := s[n] = s[n - 1] + Times @@ f @@@ FactorInteger[n]; Select[Range[1.5*10^6], Divisible[s[#], #] &]
Showing 1-2 of 2 results.

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