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%I #24 Apr 28 2017 07:36:09
%S 5,281,461,4937,25367,75997,1193909,3464389,48591863,23674667,
%T 22486333,1648510979,12708853771,25139472583,53498475287
%N a(n) = smallest prime p such that (smallest prime > p^2) == p^2 + 4n^2, n>=1.
%e 5^2+4*1^2=29, 281^2+4*2^2=78977, 461^2 + 4*3^2=212557 (all prime).
%t Table[p = 2; While[NextPrime[p^2] != p^2 + 4 n^2, p = NextPrime@ p]; p, {n, 8}] (* _Michael De Vlieger_, Apr 22 2017 *)
%o (PARI) a(n) = {forprime(p=2, , if (nextprime(p^2+1) == p^2 + 4*n^2, return (p)););} \\ _Michel Marcus_, Apr 19 2017
%Y Cf. A007491, A053000.
%K nonn,more
%O 1,1
%A _Zak Seidov_, Apr 18 2017
%E a(13)-a(15) from _Rémy Sigrist_, Apr 28 2017