a(n) = Product_{d|n} d*tau(d), where tau(k) = the number of the divisors of k (A000005).

Terms

a(0) =1a(1) =4a(2) =6a(3) =48a(4) =10a(5) =576a(6) =14a(7) =1536a(8) =162a(9) =1600a(10) =22a(11) =497664a(12) =26a(13) =3136a(14) =3600a(15) =122880a(16) =34a(17) =1679616a(18) =38a(19) =2304000a(20) =7056a(21) =7744a(22) =46a(23) =3057647616a(24) =750a(25) =10816a(26) =17496a(27) =6322176a(28) =58a(29) =3317760000