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A032380
Numbers k such that 61*2^k + 1 is prime.
0
4, 12, 48, 88, 168, 3328, 172428, 285652, 4749928
OFFSET
1,1
PROG
(Magma) [n: n in [1..3500] |IsPrime(61*2^n + 1)] // Vincenzo Librandi, Nov 20 2010
(PARI) is(n)=ispseudoprime(61*2^n+1) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
Sequence in context: A022016 A151441 A361428 * A057346 A255230 A253087
KEYWORD
nonn,hard
EXTENSIONS
More terms (from http://web.archive.org/web/20161028080239/http://www.prothsearch.net/riesel.html), Joerg Arndt, Apr 07 2013
a(9) communicated by Jeppe Stig Nielsen, Feb 25 2024
STATUS
approved