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A389767
Numbers k such that (33^k - 4^k)/29 is prime.
0
2, 3, 7, 13, 31, 211
OFFSET
1,1
COMMENTS
The definition implies that k must be a prime.
a(7) > 10^5.
LINKS
J. Brillhart et al., Factorizations of b^n +- 1, Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 3rd edition, 2002.
H. Dubner and T. Granlund, Primes of the Form (b^n+1)/(b+1), J. Integer Sequences, 3 (2000), #P00.2.7.
Eric Weisstein's World of Mathematics, Repunit.
MATHEMATICA
Select[Prime[Range[10000]], PrimeQ[(33^# - 4^#)/29] &]
KEYWORD
nonn,hard,more
AUTHOR
Robert Price, Oct 14 2025
STATUS
approved