%I #13 Jun 13 2015 00:48:56
%S 2,6,19,61,197,633,2036,6548,21061,67737,217861,700699,2253638,
%T 7248306,23312507,74979305,241153657,775615161,2494587424,8023265560,
%U 25804984685,82995786381,266936820209,858540765611
%N a(n)=2a(n-1)+3a(n-2)+2a(n-3)+3a(n-4).
%H Harvey P. Dale, <a href="/A022015/b022015.txt">Table of n, a(n) for n = 0..1000</a>
%H <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (2,3,2,3).
%F G.f.: -(((1+x)*(2+x^2))/(-1+x(2+3*x)*(1+x^2))). - _Harvey P. Dale_, May 04 2015
%t LinearRecurrence[{2,3,2,3},{2,6,19,61},30] (* _Harvey P. Dale_, May 04 2015 *)
%K nonn
%O 0,1
%A _R. K. Guy_