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a(0)=1, a(1)=6, a(n)=13*a(n-1)-36*a(n-2) for n>1.
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%I #7 Sep 08 2013 13:31:47

%S 1,6,42,330,2778,24234,215034,1923018,17258010,155125482,1395342906,

%T 12554940426,112981880922,1016786596650,9150878043258,82357097082954,

%U 741210652521114,6670882987788138,60037895350485690,540340851995941002

%N a(0)=1, a(1)=6, a(n)=13*a(n-1)-36*a(n-2) for n>1.

%C a(n)/a(n-1) tends to 9.

%F G.f.: (1-7x)/(1-13x+36x^2). a(n)=Sum_{k, 0<=k<=n}A165253(n,k)*6^(n-k).

%F a(n) = (2*9^n+3*4^n)/5. [From _Klaus Brockhaus_, Sep 26 2009]

%K nonn

%O 0,2

%A _Philippe Deléham_, Sep 14 2009