a(n) is the smallest odd number that has n middle divisors.

Terms

a(0) =1a(1) =15a(2) =1225a(3) =2145a(4) =99225a(5) =17955a(6) =893025a(7) =51975a(8) =4601025a(9) =315315a(10) =16769025a(11) =855855a(12) =12006225a(13) =2567565a(14) =108056025a(15) =6531525a(16) =385533225a(17) =11486475a(18) =225450225a(19) =16787925a(20) =1329696225a(21) =38513475a(22) =2701400625a(23) =77702625a(24) =6053618025a(25) =80405325a(26) =4846248225a(27) =101846745a(28) =2029052025a(29) =218243025