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A250842 Primes of the form 5^x + y^5 with x, y > 0.

%I A250842 #10 Dec 16 2019 20:06:31
%S A250842 37,157,1049,7901,16649,78157,615949,1048601,1049201,1064201,1890193,
%T A250842 1953157,1960901,2201957,9915749,17210393,45435449,48860893,60466181,
%U A250842 79235293,79313293,81188293,82382557,130691237,130691357,130769357,205963001,205963601
%N A250842 Primes of the form 5^x + y^5 with x, y > 0.
%H A250842 Robert Israel, <a href="/A250842/b250842.txt">Table of n, a(n) for n = 1..10000</a>
%e A250842 37 is in this sequence because 37 is prime and 5^1+2^5 = 37.
%e A250842 7901 is in this sequence because 7901 is prime and 5^3+6^5 = 7901.
%p A250842 N:= 10^10: # for terms <= N
%p A250842 Res:= NULL:
%p A250842 for x from 1 to floor(log[5](N)) do
%p A250842   for y from 2 by 2 do
%p A250842      z:= y^5 + 5^x;
%p A250842      if z > N then break fi;
%p A250842      if isprime(z) then Res:= Res, z fi
%p A250842 od od:
%p A250842 sort([Res]); # _Robert Israel_, Dec 16 2019
%t A250842 f[x_, y_]:= 5^x + y^5; lst={}; Do[p=f[x, y]; If[PrimeQ[p], AppendTo[lst, p]], {y, 50}, {x, 50}]; Take[Union[lst], 50]
%Y A250842 Cf. A250546.
%Y A250842 Cf. similar sequences listed in A250481.
%K A250842 nonn
%O A250842 1,1
%A A250842 _Vincenzo Librandi_, Nov 29 2014