a(n) = Sum_{d|n} A007955(d) * A007955(n/d), where A007955(m) = product of divisors of m.

Terms

a(0) =1a(1) =4a(2) =6a(3) =20a(4) =10a(5) =84a(6) =14a(7) =160a(8) =63a(9) =220a(10) =22a(11) =3648a(12) =26a(13) =420a(14) =480a(15) =2368a(16) =34a(17) =11988a(18) =38a(19) =16480a(20) =924a(21) =1012a(22) =46a(23) =671424a(24) =275a(25) =1404a(26) =1620a(27) =44800a(28) =58a(29) =1621860