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%I #10 Jun 13 2015 00:50:00
%S 1,7,20,52,129,315,764,1848,4465,10783,26036,62860,151761,366387,
%T 884540,2135472,5155489,12446455,30048404,72543268,175134945,
%U 422813163,1020761276,2464335720,5949432721,14363201167,34675835060,83714871292,202105577649,487926026595
%N Partial sums of A048693.
%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-1,-1).
%F a(n)=2*a(n-1)+a(n-2)+5; a(0)=1, a(1)=6.
%F a(n)=[ {(6+(7/2)*sqrt(2))(1+sqrt(2))^n - (6-(7/2)*sqrt(2))(1-sqrt(2))^n}/ 2*sqrt(2) ]-5/2.
%F G.f. ( 1+4*x ) / ( (x-1)*(x^2+2*x-1) ). - _R. J. Mathar_, Nov 08 2012
%F a(0)=1, a(1)=7, a(2)=20, a(n)=3*a(n-1)-a(n-2)-a(n-3). - _Harvey P. Dale_, Mar 29 2013
%t Accumulate[LinearRecurrence[{2,1},{1,6},30]] (* or *) LinearRecurrence[ {3,-1,-1},{1,7,20},40] (* _Harvey P. Dale_, Mar 29 2013 *)
%Y Cf. A048693, A048654, A048655.
%K easy,nonn
%O 0,2
%A _Barry E. Williams_
%E More terms from _Harvey P. Dale_, Mar 29 2013
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