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A116535 a(n) is the smallest odd prime p such that 2^n + p is not prime. 0
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 (list; graph; refs; listen; history; text; internal format)
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

Table of n, a(n) for n=0..104.

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

Cf. A000079, A000040.

Sequence in context: A238048 A010624 A019638 * A287660 A122001 A161327

Adjacent sequences:  A116532 A116533 A116534 * A116536 A116537 A116538

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Mar 27 2006

EXTENSIONS

More terms from Stefan Steinerberger, Mar 28 2006

STATUS

approved

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Last modified October 18 04:46 EDT 2019. Contains 328145 sequences. (Running on oeis4.)