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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A122846 Sequence gives k numbers from A122839.

Original entry on oeis.org

1, 9, 4, 36, 16, 9, 81, 4, 64, 35, 36, 49, 16, 25, 144, 15, 9, 16, 100, 81, 49, 4, 64, 35, 36, 196, 16, 15, 25, 49, 25, 144, 9, 60, 9, 100, 64, 100, 121, 15, 16, 81, 16, 4, 81, 9, 25, 16, 49, 4, 25, 16, 121, 25, 35, 256, 114, 36, 35, 81, 4, 49, 16, 16, 36, 4, 64
Offset: 1

Views

Author

Yasutoshi Kohmoto, Oct 23 2006

Keywords

Comments

Almost all terms are squares.

Crossrefs

Programs

  • Mathematica
    f[p_, e_] := (p^(e+1)-1)*(p^e+1)/(p-1)/(p^e-1)^2; ratio[1] = 1; ratio[n_] := Times @@ (f @@@ FactorInteger[n]); Select[ratio /@ Range[10^5], IntegerQ] (* Amiram Eldar, Dec 11 2019 *)

Formula

a(n) = f(A122839(n)), where f(m) = A000203(m)*A034448(m)/A047994(m)^2. - Amiram Eldar, Dec 11 2019

Extensions

More terms from Amiram Eldar, Dec 11 2019
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