a(n) is the smallest number k such that n*k has twice as many divisors as k.

Terms

a(0) =1a(1) =1a(2) =2a(3) =1a(4) =12a(5) =1a(6) =4a(7) =3a(8) =20a(9) =1a(10) =72a(11) =1a(12) =28a(13) =45a(14) =8a(15) =1a(16) =108a(17) =1a(18) =160a(19) =63a(20) =44a(21) =1a(22) =288a(23) =5a(24) =52a(25) =9a(26) =224a(27) =1a(28) =10800a(29) =1