a(n) is the smallest m such that A347191(m) = 2*n, where A347191(m) = tau(m^2 - 1).

Terms

a(0) =2a(1) =3a(2) =8a(3) =5a(4) =7a(5) =15a(6) =33a(7) =11a(8) =17a(9) =23a(10) =513a(11) =19a(12) =13841287200a(13) =31a(14) =73a(15) =29a(17) =49a(18) =131073a(19) =41a(20) =97a(21) =1537a(22) =31381059608a(23) =79a(24) =50626a(25) =10239a(26) =127a(27) =223a(29) =71a(31) =109a(32) =61953