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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A058221 Next-to-smallest k such that 2^(2^n) - k is prime. 1
2, 5, 15, 17, 17, 83, 173, 357, 629, 179, 2543, 8067, 5619, 29027 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..14.

PROG

(PARI) a(n) = N = 2^(2^n); N - precprime(precprime(N)-1) \\ Michel Marcus, Jun 29 2013

CROSSREFS

Cf. A058220.

Sequence in context: A146109 A146108 A032841 * A146122 A263457 A146121

Adjacent sequences:  A058218 A058219 A058220 * A058222 A058223 A058224

KEYWORD

nonn,hard,more

AUTHOR

Warren D. Smith, Nov 30 2000

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified January 28 13:18 EST 2020. Contains 331321 sequences. (Running on oeis4.)