a(n) is the least k > 0 such that A303809(k) = 2^n.

Terms

a(0) =1a(1) =2a(2) =4a(3) =12a(4) =16a(5) =48a(6) =144a(7) =720a(8) =1296a(9) =6480a(10) =32400a(11) =184320a(12) =331776a(13) =1658880a(14) =8294400a(15) =58060800a(16) =65536a(17) =196608a(18) =589824a(19) =2949120a(20) =5308416a(21) =26542080a(22) =132710400a(23) =928972800a(24) =3317760000a(25) =23224320000a(26) =162570240000