a(n) is the product of those divisors d of n such that tau(d) divides sigma(d).

Terms

a(0) =1a(1) =1a(2) =3a(3) =1a(4) =5a(5) =18a(6) =7a(7) =1a(8) =3a(9) =5a(10) =11a(11) =18a(12) =13a(13) =98a(14) =225a(15) =1a(16) =17a(17) =18a(18) =19a(19) =100a(20) =441a(21) =242a(22) =23a(23) =18a(24) =5a(25) =13a(26) =81a(27) =98a(28) =29a(29) =40500