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%I #24 Sep 08 2022 08:46:14
%S 3,6,15,19,36,75,80,118,199,336,360,520,1282,1810,2872,4870,14467,
%T 15102,22499,24675,45615,105648,116432
%N Numbers n such that 64^n - 8^n - 1 is prime.
%C For n = 3, 6, 15, 19 the corresponding primes are 261631, 68719214591, 1237940039285345090527035391, 20769187434139310370006797241024511.
%C 3*a(n) belongs to A098845 (the terms from a(18) to a(23) are derived from that sequence).
%e 3 is in the sequence because 64^3 - 8^3 - 1 = 261631 is prime.
%t Select[Range[1000], PrimeQ[64^# - 8^# - 1] &]
%o (Magma) [n: n in [0..300] | IsPrime(64^n-8^n-1)];
%o (PARI) for(n=1, 1e3, if(ispseudoprime(64^n - 8^n - 1), print1(n, ", "))) \\ _Altug Alkan_, Dec 12 2015
%Y Cf. A098845, similar sequences listed in A265481.
%K nonn,more
%O 1,1
%A _Vincenzo Librandi_, Dec 12 2015
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