%I A049683
%S A049683 0,1,20,361,6480,116281,2086580,37442161,671872320,12056259601,
%T A049683 216340800500,3882078149401,69661065888720
%N A049683 a(n)=(L(6n)-2)/16, where L=A000032 (the Lucas sequence).
%C A049683 This is the r=20 member of the r-family of sequences S_r(n), n>=1, defined 
               in A092184 where more information can be found.
%H A049683 <a href="Sindx_Ch.html#Cheby">Index entries for sequences related to 
               Chebyshev polynomials.</a>
%F A049683 a(n) = 1/16*{-2+[9+4*sqrt(5)]^n+[9-4*sqrt(5)]^n}. - R. Stephan, Apr 14 
               2004
%F A049683 a(n)=(T(n, 9)-1)/8 with Chebyshev's polynomials of the first kind evaluated 
               at x=9: T(n, 9)=A023039(n). W. Lang (wolfdieter.lang_AT_physik_DOT_uni-karlsruhe_DOT_de), 
               Oct 18 2004
%F A049683 G.f.: x*(1+x)/((1-x)*(1-18*x+x^2)) = x*(1+x)/(1-19*x+19*x^2-x^3) (from 
               the Stephan link, see A092184).
%Y A049683 Sequence in context: A053508 A060918 A115100 this_sequence A014901 A000564 
               A019580
%Y A049683 Adjacent sequences: A049680 A049681 A049682 this_sequence A049684 A049685 
               A049686
%K A049683 nonn
%O A049683 0,3
%A A049683 Clark Kimberling (ck6(AT)evansville.edu)