Least k such that (tau(k^4)+3)/4=n.

Terms

a(0) =1a(1) =2a(2) =4a(3) =8a(4) =16a(5) =32a(6) =6a(7) =128a(8) =256a(9) =512a(10) =1024a(11) =12a(12) =4096a(13) =8192a(14) =16384a(15) =32768a(16) =24a(17) =131072a(18) =262144a(19) =524288a(20) =36a(21) =48a(22) =4194304a(23) =8388608a(24) =16777216a(25) =33554432a(26) =96a(27) =134217728a(28) =268435456a(29) =72