%I A084329
%S A084329 0,1,20,380,7200,136400,2584000,48952000,927360000,17568160000,
%T A084329 332816000000,6304956800000,119442816000000,2262757184000000,
%U A084329 42866287360000000,812070603520000000,15384086323200000000
%N A084329 a(0)=0, a(1)=1, a(n)=20a(n-1)-20a(n-2).
%F A084329 a(n)=(1/8)*sum(k=0, n, binomial(n, k)*F(6*k)) where F(k) denotes the 
               k-th Fibonacci number.
%F A084329 G.f.: x/(1-20x+20x^2).
%F A084329 a(n)=-(1/40)*[10-4*sqrt(5)]^n*sqrt(5)+(1/40)*sqrt(5)*[10+4*sqrt(5)]^n, 
               with n>=0 - Paolo P. Lava (ppl(AT)spl.at), Jun 16 2008
%o A084329 (PARI) a(n)=(1/8)*sum(k=0,n,binomial(n,k)*fibonacci(6*k))
%o A084329 (PARI) a(n)=imag((6+8*quadgen(5))^n)/8
%Y A084329 Cf. A030191.
%Y A084329 Sequence in context: A014901 A000564 A019580 this_sequence A097832 A063815 
               A158534
%Y A084329 Adjacent sequences: A084326 A084327 A084328 this_sequence A084330 A084331 
               A084332
%K A084329 nonn
%O A084329 0,3
%A A084329 Benoit Cloitre (benoit7848c(AT)orange.fr), Jun 21 2003