A254081 - OEIS

%I #4 Jan 25 2015 10:18:09

%S 40320,1632960,38102400,673596000,10035083520,133102569600,

%T 1623972430080,18615386790000,203401119841920,2140495978400640,

%U 21860934514473600,217932712305073920,2130148393318725120,20485620162998625600,194378546540211264000,1823813323809879402000

%N Number of primitive (=aperiodic) n-bead necklaces with colored beads of exactly 9 different colors.

%H Alois P. Heinz, <a href="/A254081/b254081.txt">Table of n, a(n) for n = 9..1000</a>

%p with(numtheory):

%p b:= proc(n, k) option remember; `if`(n=0, 1,

%p       add(mobius(n/d)*k^d, d=divisors(n))/n)

%p     end:

%p a:= n-> add(b(n, 9-j)*binomial(9, j)*(-1)^j, j=0..9):

%p seq(a(n), n=9..30);

%Y Column k=9 of A254040.

%K nonn

%O 9,1

%A _Alois P. Heinz_, Jan 25 2015