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A056291 Number of primitive (period n) n-bead necklaces with exactly six different colored beads. 4
0, 0, 0, 0, 0, 120, 2160, 23940, 211680, 1643544, 11748240, 79419060, 516257280, 3262440960, 20193277104, 123071683140, 741419995680, 4427489935680, 26264144909520, 155018839412052, 911509010152560, 5344538372696880, 31272099902089200, 182707081042818360 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

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]

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..1000

FORMULA

Sum mu(d)*A056286(n/d) where d|n.

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, 6-j)*binomial(6, j)*(-1)^j, j=0..6):

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, 6 - j]*Binomial[6, j]*(-1)^j, {j, 0, 6}];

Table[a[n], {n, 1, 30}] (* Jean-Fran├žois Alcover, Jun 06 2018, after Alois P. Heinz *)

CROSSREFS

Cf. A032164.

Column k=6 of A254040.

Sequence in context: A293972 A144858 A084030 * A056286 A166779 A038745

Adjacent sequences:  A056288 A056289 A056290 * A056292 A056293 A056294

KEYWORD

nonn

AUTHOR

Marks R. Nester

STATUS

approved

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Last modified August 12 17:17 EDT 2020. Contains 336439 sequences. (Running on oeis4.)