A254079 Number of primitive (=aperiodic) n-bead necklaces with colored beads of exactly 7 different colors.

720, 17640, 258720, 2963520, 29317680, 263506320, 2215825920, 17758540440, 137337087888, 1033793011440, 7621696948320, 55289495222640, 396017903136240, 2808175618022544, 19754629731587280, 138087381577881960, 960370246763096400, 6652267408747194360

Offset: 7

Author

Alois P. Heinz, Jan 25 2015

Keywords

• nonn

Links

• Alois P. Heinz, Table of n, a(n) for n = 7..1000

Crossrefs

Column k=7 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, 7-j)*binomial(7, j)*(-1)^j, j=0..7):
seq(a(n), n=7..30);