cp's OEIS Frontend

A208670 Number of 2n-bead necklaces labeled with numbers 1..7 allowing reversal, with neighbors differing by exactly 1.

%I A208670 #9 Mar 22 2017 22:05:40
%S A208670 6,11,20,41,86,208,514,1398,3934,11576,34850,107303,334396,1053851,
%T A208670 3345320,10685570,34292064,110498897,357256018,1158492478,3766458404,
%U A208670 12274037845,40082339406,131144365904,429838330172,1411104048106,4639351259122,15273992343065
%N A208670 Number of 2n-bead necklaces labeled with numbers 1..7 allowing reversal, with neighbors differing by exactly 1.
%H A208670 Andrew Howroyd, <a href="/A208670/b208670.txt">Table of n, a(n) for n = 1..100</a>
%F A208670 a(n) = (2*A208726(n) + A129639(11+n))/4.
%e A208670 All solutions for n=3:
%e A208670 ..1....5....1....5....3....4....1....6....4....1....2....2....4....5....3....4
%e A208670 ..2....6....2....6....4....5....2....7....5....2....3....3....5....6....4....5
%e A208670 ..1....5....3....7....3....4....1....6....6....3....4....2....6....5....5....4
%e A208670 ..2....6....2....6....4....5....2....7....5....4....3....3....7....6....4....5
%e A208670 ..3....5....3....7....5....6....1....6....6....3....4....2....6....7....5....4
%e A208670 ..2....6....2....6....4....5....2....7....5....2....3....3....5....6....4....5
%e A208670 ..
%e A208670 ..2....2....3....3
%e A208670 ..3....3....4....4
%e A208670 ..2....4....3....5
%e A208670 ..3....5....4....6
%e A208670 ..4....4....3....5
%e A208670 ..3....3....4....4
%Y A208670 Column 7 of A208671.
%K A208670 nonn
%O A208670 1,1
%A A208670 _R. H. Hardin_, Feb 29 2012
%E A208670 a(12)-a(28) from _Andrew Howroyd_, Mar 19 2017