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.

A320071 Number of length n primitive (=aperiodic or period n) 6-ary words which are earlier in lexicographic order than any other word derived by cyclic shifts of the alphabet.

Original entry on oeis.org

1, 5, 35, 210, 1295, 7735, 46655, 279720, 1679580, 10076395, 60466175, 362789070, 2176782335, 13060647355, 78364162765, 470184704640, 2821109907455, 16926657757380, 101559956668415, 609359729932590, 3656158440016285, 21936950579911675, 131621703842267135
Offset: 1

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Author

Alois P. Heinz, Oct 05 2018

Keywords

Comments

Dirichlet convolution of mu(n) with 6^(n-1).

Crossrefs

Column k=6 of A143325.
First differences of A320090.

Programs

  • Maple
    a:= n-> add(`if`(d=n, 6^(n-1), -a(d)), d=numtheory[divisors](n)):
    seq(a(n), n=1..25);
  • Mathematica
    nmax = 20; Rest[CoefficientList[Series[Sum[MoebiusMu[k] * x^k / (1 - 6*x^k), {k, 1, nmax}], {x, 0, nmax}], x]] (* Vaclav Kotesovec, Dec 11 2020 *)

Formula

a(n) = Sum_{d|n} 6^(d-1) * mu(n/d).
a(n) = 6^(n-1) - Sum_{d
a(n) = A143325(n,6).
a(n) = A074650(n,6) * n/6.
a(n) = A143324(n,6) / 6.
G.f.: Sum_{k>=1} mu(k)*x^k/(1 - 6*x^k). - Ilya Gutkovskiy, Oct 25 2018