A207261 - OEIS

%I #18 Sep 17 2017 22:17:55

%S 10657,274200257,304606801,92205451297,22876799984497,

%T 1853020205629057,59604706692754849,523348059906214747850254177,

%U 144226335084562589858781936977,25053659285408524696023221081716801,100000000000037589973457545958193355601

%N Primes of the form x^(2*y) + y^(2*x), for x and y > 1.

%C If x or y = 1, we obtain primes of the form x^2 + 1 (or y^2 + 1) corresponding to the sequence A002496(n). The first value of this sequence, a(1) = 10657, is not of the form x^2 + 1.

%H Vincenzo Librandi, <a href="/A207261/b207261.txt">Table of n, a(n) for n = 1..50</a>

%e 10657 is in the sequence because if (x,y) = (3,4), then 3^(2*4) + 4^(2*3) = 6561 + 4096 = 10657.

%t a={}; Do[Do[k=x^(2*y)+y^(2*x); If[PrimeQ[k], AppendTo[a,k]], {x,2,y}], {y,2,200}]; Union[a]

%Y Cf. A002496, A094133, A111635.

%K nonn

%O 1,1

%A _Michel Lagneau_, Feb 16 2012