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%I #6 May 27 2016 07:28:41
%S 5,31,271,929,2789,4153
%N Numbers n such that (11^n - 9^n)/2 is prime.
%C All terms are prime.
%C The corresponding primes: 51001, 95780952266636767336259095696501, ...
%t Select[Range[1, 10000], PrimeQ[(11^# - 9^#)/2] &]
%o (PARI) for(n=1, 10000, if(isprime((11^n - 9^n)/2), print1(n, ", ")))
%Y Cf. A005808, A210506, A128027, A216181, A128347, A273598, A273599, A273600, A062577.
%K nonn,more,hard
%O 1,1
%A _Tim Johannes Ohrtmann_, May 26 2016
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