a(n) is the smallest k such that tau(k^2 + 1) is equal to 2^n, where tau = A000005 and a(n) = -1 if no such k exists.

A380969

a(n) is the smallest k such that tau(k^2 + 1) is equal to 2^n, where tau = A000005 and a(n) = -1 if no such k exists.

Terms

    a(0) =0a(1) =1a(2) =3a(3) =13a(4) =47a(5) =307a(6) =2163a(7) =17557a(8) =191807a(9) =1413443a(10) =16485763a(11) =169053487

External references