a(n) is the smallest positive k such that k^2 + 1 has 2*n divisors, or -1 if no such k exists.

Terms

a(0) =1a(1) =3a(2) =7a(3) =13a(4) =182a(5) =43a(6) =1068a(7) =47a(8) =268a(9) =443a(10) =15905182a(11) =157a(12) =1832311432a(13) =14557a(14) =16432a(15) =307a(16) =255250280182a(17) =1407a(18) =355101282318a(19) =3307a(20) =92682a(21) =3626068a(23) =993a(24) =313932a(25) =120813568a(26) =51982a(27) =16693a(29) =2943a(31) =2163