OFFSET
1,1
EXAMPLE
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.
MATHEMATICA
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 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
John L. Drost, May 22 2012
STATUS
approved