a(n) = sigma_9(2n-1).

Terms

a(0) =1a(1) =19684a(2) =1953126a(3) =40353608a(4) =387440173a(5) =2357947692a(6) =10604499374a(7) =38445332184a(8) =118587876498a(9) =322687697780a(10) =794320419872