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

Terms

a(0) =1a(1) =-5a(2) =-10a(3) =5a(4) =-26a(5) =50a(6) =-50a(7) =-5a(8) =10a(9) =130a(10) =-122a(11) =-50a(12) =-170a(13) =250a(14) =260a(15) =5a(16) =-290a(17) =-50a(18) =-362a(19) =-130a(20) =500a(21) =610a(22) =-530a(23) =50a(24) =26a(25) =850a(26) =-10a(27) =-250a(28) =-842a(29) =-1300