Dirichlet g.f.: (zeta(s-3) / zeta(s))^2.

Terms

a(0) =1a(1) =14a(2) =52a(3) =161a(4) =248a(5) =728a(6) =684a(7) =1680a(8) =2080a(9) =3472a(10) =2660a(11) =8372a(12) =4392a(13) =9576a(14) =12896a(15) =16576a(16) =9824a(17) =29120a(18) =13716a(19) =39928a(20) =35568a(21) =37240a(22) =24332a(23) =87360a(24) =46376a(25) =61488a(26) =74412a(27) =110124a(28) =48776a(29) =180544