a(n) = Sum_{i+j+k=n, i,j,k >= 1} tau(i)*tau(j)*tau(k), where tau() = A000005().

Terms

a(0) =0a(1) =0a(2) =1a(3) =6a(4) =18a(5) =41a(6) =78a(7) =132a(8) =209a(9) =306a(10) =435a(11) =591a(12) =780a(13) =1008a(14) =1268a(15) =1584a(16) =1917a(17) =2335a(18) =2751a(19) =3294a(20) =3776a(21) =4467a(22) =5034a(23) =5875a(24) =6522a(25) =7548a(26) =8250a(27) =9498a(28) =10260a(29) =11734