A353008 a(n) is the smallest positive k such that k^2 + 1 has 2*n divisors, or -1 if no such k exists.

1, 3, 7, 13, 182, 43, 1068, 47, 268, 443, 15905182, 157, 1832311432, 14557, 16432, 307, 255250280182, 1407, 355101282318, 3307, 92682, 3626068, 21346690797155182, 993, 313932, -1, 51982, 16693, -1, 2943, -1, 2163, -1, -1, -1, 3957

Offset

1,2

Links

Table of n, a(n) for n=1..36.

Crossrefs

Cf. A193432.

Sequence in context: A221211 A322301 A154821 * A084741 A135623 A172291

Adjacent sequences: A353005 A353006 A353007 * A353009 A353010 A353011

Keyword

sign

Author

Jon E. Schoenfield, May 15 2022

Status

approved