cp's OEIS Frontend

A208188 Number of distinct n-colored necklaces with 7 beads per color.

%I A208188 #10 Dec 01 2014 20:22:19
%S A208188 1,1,246,19003476,16875655269948,90784545100668913392,
%T A208188 2041012695880532470281654960,150277870737901828652705825755721760,
%U A208188 30495546426686489361833408314854897254404320,14997592385781765578538605874290442908069285068834560
%N A208188 Number of distinct n-colored necklaces with 7 beads per color.
%H A208188 Alois P. Heinz, <a href="/A208188/b208188.txt">Table of n, a(n) for n = 0..35</a>
%F A208188 a(n) = Sum_{d|7} phi(7/d)*(n*d)!/(d!^n*n*7) if n>0 and a(0) = 1.
%e A208188 a(0) =   1: the empty necklace.
%e A208188 a(1) =   1: {0000000}.
%e A208188 a(2) = 246: {00000001111111, ..., 01010101010101}.
%p A208188 with(numtheory);
%p A208188 a:= n-> `if`(n=0, 1, add(phi(7/d) *(n*d)!/(d!^n *7*n), d={1, 7})):
%p A208188 seq(a(n), n=0..12);
%Y A208188 Row n=7 of A208183.
%Y A208188 Cf. A000010, A000142.
%K A208188 nonn
%O A208188 0,3
%A A208188 _Alois P. Heinz_, Feb 24 2012