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A034923
Numbers k such that 43^k - 42 is prime.
0
4, 6, 42, 64, 65, 1017, 3390, 3894, 8904, 12976
OFFSET
1,1
COMMENTS
Related to hyperperfect numbers of a certain form.
k = 1017 produces a 1662-digit number which is only a probable prime. Any additional terms are greater than 1500.
The next terms are > 3000. - Vincenzo Librandi, Sep 27 2012
LINKS
J. S. McCranie, A study of hyperperfect numbers, J. Int. Seqs. Vol. 3 (2000) #P00.1.3.
MATHEMATICA
Select[Range[1500], PrimeQ[43^# - 42] &] (* Vincenzo Librandi, Sep 27 2012 *)
PROG
(PARI) for(n=2, 1500, if(isprime(43^n-42), print1(n, ", ")))
CROSSREFS
Sequence in context: A355233 A377682 A145387 * A013022 A012908 A306842
KEYWORD
nonn,more
AUTHOR
EXTENSIONS
a(6) from Rick L. Shepherd, Jun 21 2002
a(7)-a(8) from Michael S. Branicky, Aug 15 2021
a(9)-a(10) from Michael S. Branicky, Mar 28 2023
STATUS
approved