a(n) is the least number with exactly n divisors of the form 4*k+1.

Terms

a(0) =1a(1) =5a(2) =25a(3) =45a(4) =441a(5) =225a(6) =5103a(7) =585a(8) =1575a(9) =2205a(10) =35721a(11) =2925a(12) =194481a(13) =25515a(14) =11025a(15) =9945a(16) =2893401a(17) =17325a(18) =2711943423a(19) =28665a(20) =127575a(21) =178605a(22) =480249a(23) =45045a(24) =275625a(25) =972405a(26) =121275a(27) =266805a(28) =18983603961a(29) =143325