Sum of the divisors of 2^n - 1.

Terms

a(0) =1a(1) =4a(2) =8a(3) =24a(4) =32a(5) =104a(6) =128a(7) =432a(8) =592a(9) =1536a(10) =2160a(11) =8736a(12) =8192a(13) =22528a(14) =38912a(15) =111456a(16) =131072a(17) =473600a(18) =524288a(19) =1999872a(20) =2466048a(21) =5909760a(22) =8567136a(23) =38054016a(24) =34713728a(25) =89522176a(26) =155493536a(27) =462274560a(28) =539922240a(29) =2015330304