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.

A056290 Number of primitive (period n) n-bead necklaces with exactly five different colored beads.

Original entry on oeis.org

0, 0, 0, 0, 24, 300, 2400, 15750, 92680, 510288, 2691600, 13793850, 69309240, 343499100, 1686135352, 8221421250, 39901776360, 193053923860, 932142850800, 4495236287850, 21664357532920, 104388118174500, 503044634004000, 2425003910574000, 11696087875731600
Offset: 1

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Author

Keywords

Comments

Turning over the necklace is not allowed.

References

  • M. R. Nester (1999). Mathematical investigations of some plant interaction designs. PhD Thesis. University of Queensland, Brisbane, Australia. [See A056391 for pdf file of Chap. 2]

Crossrefs

Cf. A001692.
Column k=5 of A254040.

Programs

  • Maple
    with(numtheory):
    b:= proc(n, k) option remember; `if`(n=0, 1,
          add(mobius(n/d)*k^d, d=divisors(n))/n)
        end:
    a:= n-> add(b(n, 5-j)*binomial(5, j)*(-1)^j, j=0..5):
    seq(a(n), n=1..30);  # Alois P. Heinz, Jan 25 2015
  • Mathematica
    b[n_, k_] := b[n, k] = If[n==0, 1, DivisorSum[n, MoebiusMu[n/#]*k^# &]/n];
    a[n_] := Sum[b[n, 5 - j]*Binomial[5, j]*(-1)^j, {j, 0, 5}];
    Table[a[n], {n, 1, 30}] (* Jean-François Alcover, Jun 06 2018, after Alois P. Heinz *)

Formula

sum mu(d)*A056285(n/d) where d|n.