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%I #19 Dec 01 2014 09:17:20
%S 3,5,11,13,17,29,41,53,73,83,89,97,113,137,173,227,229,233,241,257,
%T 281,293,337,353,443,449,457,521,569,593,617,641,733,761,857,881,953,
%U 977,1033,1049,1091,1093,1097,1153,1193,1217,1229,1249,1289,1373
%N Primes of the form 2^x + y^2 with x, y > 0.
%e 11 is in the sequence because 2^1+3^2 = 11.
%e 97 is in the sequence because 2^4+9^2 = 97.
%t f[x_,y_]:=2^x + y^2; lst={};Do[p=f[x, y]; If[PrimeQ[p], AppendTo[lst, p]], {y, 50}, {x, 50}]; Take[Union[lst], 50]
%Y Cf. A248346.
%Y Cf. primes of the type k^x+y^k: this sequence (k=2), A250716 (k=3), A250717 (k=4), A250842 (k=5), A250843 (k=6), A250844 (k=7).
%K nonn
%O 1,1
%A _Vincenzo Librandi_, Nov 24 2014