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A109216 Smallest factor of 2^(2n+1)+(2n+1)^2. 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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

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

MATHEMATICA

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

CROSSREFS

Cf. A064539, A109215.

Sequence in context: A140519 A285740 A174506 * A090478 A231785 A195421

Adjacent sequences:  A109213 A109214 A109215 * A109217 A109218 A109219

KEYWORD

base,nonn

AUTHOR

Zak Seidov, Jun 24 2005

EXTENSIONS

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

STATUS

approved

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Last modified April 18 12:34 EDT 2019. Contains 322209 sequences. (Running on oeis4.)