a(1)=1; for n > 1, a(n) is the smallest number with the same number of divisors as 2*a(n-1).

Terms

a(0) =1a(1) =2a(2) =4a(3) =6a(4) =12a(5) =24a(6) =48a(7) =60a(8) =120a(9) =240a(10) =360a(11) =720a(12) =1260a(13) =2520a(14) =5040a(15) =10080a(16) =20160a(17) =27720a(18) =55440a(19) =110880a(20) =221760a(21) =332640a(22) =665280a(23) =1081080a(24) =2162160a(25) =4324320a(26) =8648640a(27) =17297280a(28) =21621600a(29) =43243200