%I A006980 M1411
%S A006980 1,2,5,12,28,64,143,315,687,1485,3186,6792,14401,30391,63872,133751,
%T A006980 279177,581040,1206151,2497895,5161982,10646564,21919161,45052841,
%U A006980 92461171,189489255,387830160,792810956,1618840800,3301999647
%N A006980 Compositions: 6th column of A048004.
%D A006980 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A006980 J. L. Yucas, Counting special sets of binary Lyndon words, Ars Combin., 
               31 (1991), 21-29.
%F A006980 G.f.: x^6 / ((1-x-x^2-x^3-x^4-x^5) * (1-x-x^2-x^3-x^4-x^5-x^6)). [From 
               Alois P. Heinz (heinz(AT)hs-heilbronn.de), Oct 29 2008]
%p A006980 a:= n-> (Matrix(11, (i,j)-> if i=j-1 then 1 elif j=1 then [2, 1, 0, -1, 
               -2, -4, -5, -4, -3, -2, -1][i] else 0 fi)^n) [1,7]: seq (a(n), n=6..40); 
               [From Alois P. Heinz (heinz(AT)hs-heilbronn.de), Oct 29 2008]
%Y A006980 Sequence in context: A111586 A006979 A019301 this_sequence A045623 A001410 
               A019486
%Y A006980 Adjacent sequences: A006977 A006978 A006979 this_sequence A006981 A006982 
               A006983
%K A006980 nonn
%O A006980 6,2
%A A006980 Simon Plouffe (simon.plouffe(AT)gmail.com)
%E A006980 More terms and better definition from Alois P. Heinz (heinz(AT)hs-heilbronn.de), 
               Oct 29 2008
%E A006980 Corrected definition: 6th column of A048004. - Geoffrey Critzer (critzer.geoffrey(AT)usd443.org), 
               Nov 09 2008