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.

A128391 A054523^24 * A000594.

Original entry on oeis.org

1, 0, 300, -1724, 4926, 0, -16600, 44600, -100299, 0, 534852, -517200, -577450, 0, 1477800, 2486626, -6905550, 0, 10661852, -8492424, -4980000, 0, 18643800, 13380000, -25030649, 0, -78396200, 28618400, 128407302, 0, -52842448, -150834520, 160455600, 0, -81771600
Offset: 1

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Author

Gary W. Adamson, Feb 28 2007

Keywords

Comments

Conjecture: Given A054523^k, k = any positive integer, "zero" appears only in the sequence A018391 (k=24).
Each application of A054523 corresponds to the Dirichlet convolution of A000010 with the sequence on the right. Since both A000594 and A000010 are multiplicative, the resulting sequence will also be multiplicative. - Andrew Howroyd, Aug 03 2018

Crossrefs

Programs

  • Mathematica
    nmax = 40;
    T[n_, k_] := If[Divisible[n, k], EulerPhi[n/k], 0]; T[1, 1] = 1;
    M = Table[T[n, k], {n, 1, nmax}, {k, 1, nmax}];
    MatrixPower[M, 24].RamanujanTau[Range[nmax]] (* Jean-François Alcover, Sep 20 2019 *)
  • PARI
    seq(n, k=24)={my(u=vector(n,n,eulerphi(n)), v=vector(n,n,ramanujantau(n))); for(i=1, k, v=dirmul(u,v)); v} \\ Andrew Howroyd, Aug 03 2018

Formula

A054523^24 as an infinite lower triangular matrix * A000594.

Extensions

a(7) corrected and terms a(11) and beyond from Andrew Howroyd, Aug 03 2018