Coefficient of q^1 in nu(n), where nu(0)=1, nu(1)=b and, for n>=2, nu(n)=b*nu(n-1)+lambda*(1+q+q^2+...+q^(n-2))*nu(n-2) with (b,lambda)=(2,1).

A074084

Coefficient of q^1 in nu(n), where nu(0)=1, nu(1)=b and, for n>=2, nu(n)=b*nu(n-1)+lambda*(1+q+q^2+...+q^(n-2))*nu(n-2) with (b,lambda)=(2,1).

Terms

    a(0) =0a(1) =0a(2) =0a(3) =2a(4) =9a(5) =32a(6) =102a(7) =306a(8) =883a(9) =2480a(10) =6828a(11) =18514a(12) =49597a(13) =131568a(14) =346194a(15) =904738a(16) =2350695a(17) =6076960a(18) =15641304a(19) =40103778a(20) =102473969a(21) =261046144a(22) =663180222a(23) =1680628946a(24) =4249496795a(25) =10722962256a(26) =27007159428a(27) =67904097074

External references