a(n) is the product of the Zumkeller divisors of n.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =6a(6) =1a(7) =1a(8) =1a(9) =1a(10) =1a(11) =72a(12) =1a(13) =1a(14) =1a(15) =1a(16) =1a(17) =6a(18) =1a(19) =20a(20) =1a(21) =1a(22) =1a(23) =1728a(24) =1a(25) =1a(26) =1a(27) =28a(28) =1a(29) =180