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A116535
a(n) is the smallest odd prime p such that 2^n + p is not prime.
1
3, 7, 5, 7, 5, 3, 5, 5, 3, 3, 3, 3, 5, 3, 3, 5, 5, 3, 5, 3, 3, 3, 3, 3, 3, 3, 3, 3, 5, 3, 5, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 5, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 5, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 5, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3
OFFSET
0,1
COMMENTS
The sequence is bounded, namely {a(n)} = {3, 5, 7}, because one of the numbers 2^n + 3, 2^n + 5, 2^n + 7 is divisible by 3. - Thomas Ordowski, Apr 11 2019
LINKS
EXAMPLE
A000079(20) + a(20) = 1048576 + 3 = 1048579 = 7*163*919.
MATHEMATICA
Table[p := 2; While[PrimeQ[2^n + Prime[p]], p++ ]; Prime[p], {n, 0, 150}] (* Stefan Steinerberger, Mar 28 2006 *)
CROSSREFS
Sequence in context: A238048 A010624 A019638 * A287660 A122001 A161327
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Mar 27 2006
EXTENSIONS
More terms from Stefan Steinerberger, Mar 28 2006
STATUS
approved