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%I
%S 1,5,50,400,3500,29500,252500,2147500,18312500,155987500,1329312500,
%T 11326187500,96510312500,822337187500,7006995312500,59705092187500,
%U 508735320312500,4334829367187500,36936206445312500,314725913242187500
%N a(n)=5*a(n-1)+30*a(n-2) for n>=3, a(0)=1, a(1)=5, a(2)=50 .
%F G.f.: (1-5*x^2)/(1-5*x-30*x^2) . a(n) = Sum_{k, 0<=k<=n}A122950(n,k)*5^k .
%F a(n)=(5/2)*[(5/2)-(1/2)*sqrt(145)]^(n-1)-(15/58)*[(5/2)-(1/2)*sqrt(145)]^(n-1)*sqrt(145)+(15/58)*sqrt(145) *[(5/2)+(1/2)*sqrt(145)]^(n-1)+(5/2)*[(5/2)+(1/2)*sqrt(145)]^(n-1)+(1/6)*[C(2*n,n) mod 2], with n>=0
%K easy,nonn
%O 0,2
%A _Philippe Deléham_, Dec 31 2007
%E Corrected formula. - _Paolo P. Lava_, Nov 24 2008
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