%I A087206
%S A087206 1,4,12,40,128,416,1344,4352,14080,45568,147456,477184,1544192,4997120,
%T A087206 16171008,52330496,169345024,548012032,1773404160,5738856448,
%U A087206 18571329536,60098084864,194481487872,629355315200,2036636581888
%N A087206 a(n)=2a(n-1)+4a(n-2),a(0)=1,a(1)=4.
%C A087206 Binomial transform of A056487. Unsigned version of A152174.
%F A087206 G.f.: (1+2x)/(1-2x-4x^2); a(n)=(1-sqrt(5))^n(1/2-3sqrt(5)/10)+(1+sqrt(5))^n(1/
               2+3sqrt(5/10)).
%F A087206 a(n)=2^nFib(n+2). - Paul Barry (pbarry(AT)wit.ie), Mar 22 2004
%F A087206 a(n)=((1+sqrt5)^n-(1-sqrt5)^n)/sqrt80. Offset 2. a(4)=12. [From Al Hakanson 
               (hawkuu(AT)gmail.com), Apr 11 2009]
%Y A087206 Cf. A060925.
%Y A087206 Equals (1/2) * A063727(n-1). Cf. A006483.
%Y A087206 Sequence in context: A126986 A090576 A152174 this_sequence A081875 A102433 
               A100320
%Y A087206 Adjacent sequences: A087203 A087204 A087205 this_sequence A087207 A087208 
               A087209
%K A087206 easy,nonn
%O A087206 0,2
%A A087206 Paul Barry (pbarry(AT)wit.ie), Aug 25 2003
%E A087206 Corrected comment. - Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Nov 27 
               2008