A109216 Smallest factor of 2^(2n+1)+(2n+1)^2.

3, 17, 3, 3, 593, 3, 3, 32993, 3, 3, 2097593, 3, 3, 73, 3, 3, 8589935681, 3, 3, 17, 3, 3, 11, 3, 3, 83, 3, 3, 11, 3, 3, 17, 3, 3, 857, 3, 3, 71329, 3, 3, 59, 3, 3, 19, 3, 3, 11, 3, 3, 17, 3, 3, 4561633, 3, 3, 2940725100673, 3, 3, 193, 3, 3, 1867, 3, 3, 17, 3, 3, 44449, 3, 3, 19, 3, 3

Offset: 0

Author

Zak Seidov, Jun 24 2005

Keywords

• base
• nonn

Comments

For n={0, 1, 4, 7, 10, 16, 1003, 1063, 1879, 14677, 17326, 28642, 49534} we have the only primes of the form 2^(2n+1)+(2n+1)^2: A064539. Cases 2n+1 == 1, 2 (mod 3) are trivial and may be omitted.

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..100

Crossrefs

Cf. A064539, A109215.

Programs

Mathematica

Table[ With[ {k=2}, FactorInteger[ n^k + k^n]] [[1, 1]], {n, 1, 145, 2}]

Extensions

More terms from Robert G. Wilson v, Jun 24 2005