Product of lowest and highest prime factors of 2^n-1.

Terms

a(0) =9a(1) =49a(2) =15a(3) =961a(4) =21a(5) =16129a(6) =51a(7) =511a(8) =93a(9) =2047a(10) =39a(11) =67092481a(12) =381a(13) =1057a(14) =771a(15) =17179607041a(16) =219a(17) =274876858369a(18) =123a(19) =2359a(20) =2049a(21) =8388607a(22) =723a(23) =55831a(24) =24573a(25) =1838599a(26) =381a(27) =486737a(28) =993a(30) =196611