The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A123646 Smallest generalized Fermat prime of the form a^(2^n) + b^(2^n), where bases a,b>1; or -1 if no such prime exists. 0
 5, 13, 97, 2070241, 4338014017, 3512911982806776822251393039617, 4457915690803004131256192897205630962697827851093882159977969339137, 1638935311392320153195136107636665419978585455388636669548298482694235538906271958706896595665141002450684974003603106305516970574177405212679151205373697500164072550932748470956551681 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 LINKS Eric Weisstein's World of Mathematics, Generalized Fermat Number. MATHEMATICA Do[f=Min[Select[Take[Union[ Flatten[ Table[ i^(2^n) + j^(2^n), {i, 2, 300}, {j, 2, 300} ] ] ], 500], PrimeQ]]; Print[{n, f}], {n, 0, 7}] CROSSREFS Cf. A000215 (Fermat numbers: 2^(2^n) + 1), A019434 (Fermat primes of the form 2^(2^n) + 1). Cf. A111635 (allows one of a,b to be 1). Sequence in context: A306167 A107171 A309532 * A123622 A337749 A117340 Adjacent sequences:  A123643 A123644 A123645 * A123647 A123648 A123649 KEYWORD nonn AUTHOR Alexander Adamchuk, Nov 14 2006 EXTENSIONS Offset corrected by Jeppe Stig Nielsen, Nov 14 2019 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 September 24 17:11 EDT 2021. Contains 347651 sequences. (Running on oeis4.)