login
This site is supported by donations to The OEIS Foundation.

 

Logo


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

Table of n, a(n) for n=1..10.

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified November 19 11:20 EST 2018. Contains 317351 sequences. (Running on oeis4.)