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!)
 A140331 Smallest k such that 3^(3^n) - k is prime. 0
 4, 2, 26, 10, 466, 506, 128, 13342, 5974, 8410 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS This is to 3 as A058220 is to 2. LINKS FORMULA a(n) = A064722(A055777(n)). - Michel Marcus, Jan 28 2015 EXAMPLE a(4) = 10 because 3^(3^4) - 10 = 443426488243037769948249630619149892793 is prime. MATHEMATICA lst={}; Do[Do[p=3^(3^n)-k; If[PrimeQ[p], AppendTo[lst, k]; Break[]], {k, 2, 11!}], {n, 7}]; lst (* Vladimir Joseph Stephan Orlovsky, Apr 27 2010 *) PROG (PARI) a(n) = x = 3^(3^n); x - precprime(x); \\ Michel Marcus, Jan 28 2015 CROSSREFS Cf. A055777 (3^(3^n)), A058220. Sequence in context: A298593 A228474 A058167 * A095896 A286798 A123670 Adjacent sequences:  A140328 A140329 A140330 * A140332 A140333 A140334 KEYWORD more,nonn AUTHOR Jonathan Vos Post, May 26 2008 EXTENSIONS a(5)-a(8) from Cino Hilliard, Jun 02 2008 a(9)-a(10) from Donovan Johnson, Sep 13 2008 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 23 19:48 EDT 2021. Contains 347617 sequences. (Running on oeis4.)