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%I #9 Dec 09 2017 04:01:15
%S 2633,587,1777,2633,239521,862471,2017,208457,586273,147451,4951,
%T 586273,207073,612553,102871,208457,301681,351439,242447,2076901,
%U 55948657,27487,119503,9425257,239521,5188507,128467,75853,74049413
%N a(n) is the smallest prime such that it and the previous four primes are all of the form x^2 + n * y^2.
%e a(7)=2017 since 2017 = 225 + 7*256, 2011 = 1444 + 7*81, 2003 = 1156 + 7*121, 1999 = 1936 + 7*9, and 1997 = 625 + 7*196 are all consecutive primes.
%t Table[again = True; lim = 10; While[again, lim2 = lim/Sqrt[n]; t = PrimePi[Select[Union[Flatten[Table[x^2 + n y^2, {x, 0, lim}, {y, 0, lim2}]]], # < lim^2 && PrimeQ[#] &]]; pos = Position[Partition[Differences[t], 4, 1], {1, 1, 1, 1}, 1, 1]; If[pos != {}, again = False; ans = Prime[t[[pos[[1, 1]] + 4]]], lim = 10*lim]]; ans, {n, 20}] (* _T. D. Noe_, May 23 2012 *)
%K nonn
%O 1,1
%A _John L. Drost_, May 22 2012
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