G.f.: (x^2+x-1)*(1+2*x+S)*(1-5*x+2*x^2+(3*x-1)*S)^2*(-1+3*x+2*x^2+(1-x)*S), where S=sqrt(1-4*x).

A135925

G.f.: (x^2+x-1)*(1+2*x+S)*(1-5*x+2*x^2+(3*x-1)*S)^2*(-1+3*x+2*x^2+(1-x)*S), where S=sqrt(1-4*x).

Terms

    a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =0a(6) =-16a(7) =0a(8) =80a(9) =240a(10) =656a(11) =1936a(12) =6000a(13) =19088a(14) =61792a(15) =202832a(16) =673888a(17) =2263392a(18) =7677712a(19) =26280800a(20) =90709616a(21) =315486768a(22) =1104982560a(23) =3895248720a(24) =13813470240a(25) =49256281920a(26) =176536299168a(27) =635710344672

External references