|
%I #10 Mar 20 2017 09:50:15
%S 4,7,12,23,44,97,212,512,1260,3251,8540,23035,62780,173453,482692,
%T 1353077,3811364,10785235,30625196,87239999,249174236,713416601,
%U 2046945140,5884580074,16946835092,48883925867,141217957620,408519816611,1183291934300,3431535849813
%N Number of 2n-bead necklaces labeled with numbers 1..5 allowing reversal, with neighbors differing by exactly 1.
%H Andrew Howroyd, <a href="/A208668/b208668.txt">Table of n, a(n) for n = 1..100</a>
%F a(n) = (2*A208724(n) + A090993(n))/4. - _Andrew Howroyd_, Mar 19 2017
%e All solutions for n=3:
%e ..3....3....1....1....1....2....2....3....1....2....2....4
%e ..4....4....2....2....2....3....3....4....2....3....3....5
%e ..5....3....1....1....3....2....4....3....3....2....4....4
%e ..4....4....2....2....2....3....5....4....4....3....3....5
%e ..5....5....3....1....3....2....4....3....3....4....4....4
%e ..4....4....2....2....2....3....3....4....2....3....3....5
%Y Column 5 of A208671.
%K nonn
%O 1,1
%A _R. H. Hardin_, Feb 29 2012
%E a(13)-a(30) from _Andrew Howroyd_, Mar 19 2017
| 