The OEIS is supported by the many generous donors to the OEIS Foundation.

 Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 60th year, we have over 367,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A090875 a(n) is the smallest number m such that m^(2^k) + 2^(2^k) is prime for k=0,1,...,n. 2
 1, 1, 1, 1, 1, 2321204055, 37185086099807 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,6 COMMENTS The first five terms of this sequence correspond to Fermat primes. According to the answers to Prime Puzzle 399 (see link), a(6) is larger than 2.3*10^12. - M. F. Hasler, Aug 02 2007 LINKS Table of n, a(n) for n=0..6. Carlos Rivera (ed.), Puzzle 399. Some more terms, The Prime Puzzles and Problems Connection. EXAMPLE a(5)=2321204055 because 2321204055 is the smallest number m such that m^(2^k) + 2^(2^k) is prime for k=0,1,2,3,4 and 5. CROSSREFS Cf. A090872, A090873, A090874. Sequence in context: A251490 A277720 A333664 * A132907 A038685 A017289 Adjacent sequences: A090872 A090873 A090874 * A090876 A090877 A090878 KEYWORD nonn AUTHOR Farideh Firoozbakht, Feb 06 2004 EXTENSIONS a(6) found by Kellen Shenton sent in by Jeppe Stig Nielsen, Apr 06 2022 STATUS approved

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

Last modified December 2 14:00 EST 2023. Contains 367524 sequences. (Running on oeis4.)