%I
%S 1,8,26,63,136,272,521,968,1762,3159,5600,9840,17169,29784,51418,
%T 88399,151432,258592,440345,747960,1267586,2143783,3618816,6098208,
%U 10260001,17236712,28918106,48454623,81093832,135569264,226404905
%N Principal diagonal of the convolution array A213768.
%H Clark Kimberling, <a href="/A213769/b213769.txt">Table of n, a(n) for n = 1..1000</a>
%H <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (4,4,2,4,0,1).
%F a(n) = 4*a(n1)  4*a(n2)  2*a(n3) + 4*a(n4)  a(n6).
%F G.f.: f(x)/g(x), where f(x) = x*(1 + 4*x  2*x^2  7*x^3) and g(x) = (1  2*x + x^3 )^2.
%t (See A213768.)
%t LinearRecurrence[{4,4,2,4,0,1},{1,8,26,63,136,272},40] (* _Harvey P. Dale_, Jan 08 2015 *)
%Y Cf. A213768, A213500.
%K nonn,easy
%O 1,2
%A _Clark Kimberling_, Jun 21 2012
