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%I #5 Oct 31 2013 12:17:35
%S 2,4,2,14,10,26,8,80,20,20,110,64,8,16,110,106,10,280,8,166,92,364,68,
%T 310,130,836,70,364,238,434,892,1844,58,140,10,740,482,1274,308,494,
%U 1220,2644,790,646,2248,2456,422,314,1072,1124,782,200,98,1826,1502
%N a(n) is the minimal k such that 3^n +/- k are primes.
%e First term (at n=2) is a(2)=2 because 3^2 +/- 2 are primes; second term (at n=3) is a(3)=4 because 3^3 +/- 4 are primes.
%t f[n_] := Block[{k = 2}, While[ !PrimeQ[3^n + k] || !PrimeQ[3^n - k], k += 2]; k]; Table[ f[n], {n, 2, 56}] (* _Robert G. Wilson v_ *)
%K nonn
%O 2,1
%A _Zak Seidov_, Jan 13 2006
%E Corrected and extended by _Robert G. Wilson v_, Jan 18 2006
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