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A026053 (d(n)-r(n))/5, where d = A008778 and r is the periodic sequence with fundamental period (0,3,1,0,1).

%I A026053 #7 Dec 19 2012 15:50:09
%S A026053 1,2,5,9,14,21,29,40,53,68,86,106,130,157,187,221,258,300,346,396,451,
%T A026053 510,575,645,720,801,887,980,1079,1184,1296,1414,1540,1673,1813,1961,
%U A026053 2116,2280,2452,2632,2821,3018,3225,3441,3666,3901,4145,4400,4665,4940,5226,5522,5830,6149,6479,6821
%N A026053 (d(n)-r(n))/5, where d = A008778 and r is the periodic sequence with fundamental period (0,3,1,0,1).
%F A026053 a(n)=(n + 2)*(n^2 + 10*n + 15)/30 - 1/5*(1 + ( - 1/2 + 3/10*5^(1/2))*cos(2*n*Pi/5) + (1/5*2^(1/2)*(5 + 5^(1/2))^(1/2) + 1/10*2^(1/2)*(5 - 5^(1/2))^(1/2))*sin(2*n*Pi/5) + ( - 1/2 - 3/10*5^(1/2))*cos(4*n*Pi/5) + ( - 1/10*2^(1/2)*(5 + 5^(1/2))^(1/2) + 1/5*2^(1/2)*(5 - 5^(1/2))^(1/2))*sin(4*n*Pi/5)) [From _Richard Choulet_, Dec 14 2008]
%F A026053 a(n)= 3*a(n-1) -3*a(n-2) +a(n-3) +a(n-5) -3*a(n-6) +3*a(n-7) -a(n-8). G.f.: -x^2*(-1+x-2*x^2+x^3)/( (x^4+x^3+x^2+x+1) * (x-1)^4 ). [From _R. J. Mathar_, Oct 05 2009]
%Y A026053 A152892 [From _Richard Choulet_, Dec 14 2008]
%K A026053 nonn
%O A026053 2,2
%A A026053 _Clark Kimberling_