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.

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A375195 Numbers k such that A025487(k) and A025487(k+1) have an equal number of divisors.

Original entry on oeis.org

4, 8, 15, 22, 69, 116, 122, 134, 135, 168, 208, 278, 400, 453, 538, 584, 718, 1019, 1409, 1671, 1799, 2035, 2417, 2541, 2595, 2783, 3424, 3809, 3860, 4415, 5628, 6267, 6672, 6745, 6872, 6873, 7277, 9436, 9845, 10182, 10191, 10936, 11272, 11472, 12105, 16139, 16277
Offset: 1

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Author

Amiram Eldar, Aug 04 2024

Keywords

Comments

Numbers k such that A146288(k) = A146288(k+1).
The corresponding values of A146288(k) are 4, 8, 12, 16, 48, 48, 96, 80, 80, ... .
The corresponding values of A025487(k) are 6, 24, 72, 210, 5400, ... (A375196).
Numbers k such that A146288(k) = A146288(k+1) = A146288(k+2) are 134, 6872, 6699401, 12421946, ... .

Examples

			4 is a term since A146288(4) = A146288(5) = 4.
		

Crossrefs

Programs

  • Mathematica
    With[{lps = Cases[Import["https://oeis.org/A025487/b025487.txt", "Table"], {, }][[;; , 2]]}, Position[Differences[DivisorSigma[0, lps]], 0] // Flatten]

Formula

A025487(a(n)) = A375196(n).
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