This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 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 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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

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