

A032194


Number of necklaces with 9 black beads and n9 white beads.


2



1, 1, 5, 19, 55, 143, 335, 715, 1430, 2704, 4862, 8398, 14000, 22610, 35530, 54484, 81719, 120175, 173593, 246675, 345345, 476913, 650325, 876525, 1168710, 1542684, 2017356, 2615104, 3362260, 4289780, 5433736, 6835972
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OFFSET

9,3


COMMENTS

The g.f. is Z(C_9,x)/x^9, the 9variate cycle index polynomial for the cyclic group C_9, with substitution x[i]>1/(1x^i), i=1,...,9. Therefore by Polya enumeration a(n+9) is the number of cyclically inequivalent 9necklaces whose 9 beads are labeled with nonnegative integers such that the sum of labels is n, for n=0,1,2,... See A102190 for Z(C_9,x). See the comment in A032191 on the equivalence of this problem with the one given in the `Name' line.  Wolfdieter Lang, Feb 15 2005


LINKS

Table of n, a(n) for n=9..40.
C. G. Bower, Transforms (2)
F. Ruskey, Necklaces, Lyndon words, De Bruijn sequences, etc.
F. Ruskey, Necklaces, Lyndon words, De Bruijn sequences, etc. [Cached copy, with permission, pdf format only]
Index entries for sequences related to necklaces


FORMULA

"CIK[ 9 ]" (necklace, indistinct, unlabeled, 9 parts) transform of 1, 1, 1, 1...
G.f.: (x^9)*(15*x+14*x^218*x^3+21*x^421*x^5+25*x^6 21*x^7 +21*x^8 18*x^9 +14*x^10 5*x^11 +x^12) / ((1x)^6*(1x^3)^2*(1x^9)).
G.f.: (1/9)*x^9*(1/(1x)^9+2/(1x^3)^3+6/(1x^9)^1).  Herbert Kociemba, Oct 22 2016


MATHEMATICA

k = 9; Table[Apply[Plus, Map[EulerPhi[ # ]Binomial[n/#, k/# ] &, Divisors[GCD[n, k]]]]/n, {n, k, 30}] (* Robert A. Russell, Sep 27 2004 *)


CROSSREFS

Column k=9 of A047996.
Cf. A004526, A007997, A008610, A008646, A032191, A032192, A032193.
Sequence in context: A281156 A060100 A053733 * A024532 A036421 A295776
Adjacent sequences: A032191 A032192 A032193 * A032195 A032196 A032197


KEYWORD

nonn


AUTHOR

Christian G. Bower


STATUS

approved



