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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A145644 Cubefree part of 10^n.

Original entry on oeis.org

1, 10, 100, 1, 10, 100, 1, 10, 100, 1, 10, 100, 1, 10, 100, 1, 10, 100, 1, 10, 100, 1, 10, 100, 1, 10, 100, 1, 10, 100, 1, 10, 100, 1, 10, 100, 1, 10, 100, 1, 10, 100, 1, 10, 100, 1, 10, 100, 1, 10, 100, 1, 10, 100, 1, 10, 100, 1, 10, 100, 1, 10, 100, 1, 10, 100, 1, 10, 100
Offset: 0

Views

Author

Artur Jasinski, Oct 15 2008

Keywords

Comments

Period 3: repeat [1, 10, 100].

Links

Crossrefs

Cf. A004709, A010872, A011557, A050985, A069705, A145642, A145643.

Programs

  • Magma
    &cat [[1, 10,100]^^30]; // Wesley Ivan Hurt, Apr 18 2021
  • Mathematica
    CubefreePart[n_Integer?Positive] := Times @@ Power @@@ ({#[[1]], Mod[ #[[2]], 3]} & /@ FactorInteger[n]); Table[CubefreePart[10^n], {n, 1, 40}]
PadRight[{}, 50, {1, 10, 100}] (* Wesley Ivan Hurt, Apr 18 2021 *)

Formula

a(n) = 10^(n mod 3) = A050985(A011557(n)) = A011557(A010872(n)). - Amiram Eldar, Feb 14 2021
From Wesley Ivan Hurt, Apr 18 2021: (Start)
G.f.: (1+10*x+100*x^2)/(1-x^3).
a(n) = a(n-3). (End)

Extensions

Offset corrected by Amiram Eldar, Feb 14 2021
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