%I A154996
%S A154996 1,1,9,65,505,3825,29225,222625,1697625,12940625,98655625,752090625,
%T A154996 5733565625,43709640625,333219515625,2540290390625,19365842265625,
%U A154996 147635019140625,1125491941015625,8580160087890625,65410639259765625
%N A154996 a(n)=5*a(n-1)+20*a(n-2), n>2 ; a(0)=1, a(1)=1, a(2)=9 .
%F A154996 G.f.: (1-4*x-16*x^2)/(1-5*x-20*x^2) . a(n+1)=Sum_{k, 0<=k<=n}A154929(n,
               k)*4^(n-k).
%F A154996 a(n)=(1/2)*{[(5/2)-(1/2)*sqrt(105)]^(n-1)+[(5/2)+(1/2)*sqrt(105)]^(n-1)}+(13/
               210)*sqrt(105)*{[(5/2)+(1/2)*sqrt(105)]^(n-1)-[(5/2)-(1/2)*sqrt(105)]^(n-1)}+(4/
               5)*[C(2*n,n) mod 2], with n>=0 [From Paolo P. Lava (ppl(AT)spl.at), 
               Jan 20 2009]
%Y A154996 Sequence in context: A037548 A036731 A020234 this_sequence A128195 A103459 
               A100311
%Y A154996 Adjacent sequences: A154993 A154994 A154995 this_sequence A154997 A154998 
               A154999
%K A154996 nonn
%O A154996 0,3
%A A154996 Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Jan 18 2009