The sum of 2^((d-1)/2) over all divisors of 2n+1.

Terms

a(0) =1a(1) =3a(2) =5a(3) =9a(4) =19a(5) =33a(6) =65a(7) =135a(8) =257a(9) =513a(10) =1035a(11) =2049a(12) =4101a(13) =8211a(14) =16385a(15) =32769a(16) =65571a(17) =131085a(18) =262145a(19) =524355a(20) =1048577a(21) =2097153a(22) =4194455a(23) =8388609a(24) =16777225a(25) =33554691a(26) =67108865a(27) =134217765a(28) =268435971a(29) =536870913