%I A090873
%S A090873 1,1,218368,9324385,6628674,601,365082,532253,449140,4193407,175746,
%T A090873 2857547,2752708,6315245,80612,3354745,10892,953,6577504,157437,2247676,
%U A090873 11357637,7650,272935,318784,8034141,1158380,22315,610550,340357
%N A090873 a(n) is the smallest number m such that n^2^k + m^2^k is prime for k=0,
               1,2,3 and 4.
%F A090873 a[n_] := (For[m=1, !(PrimeQ[m+n]&&PrimeQ[m^2+n^2]&&PrimeQ[m^4+n^4]&& 
               PrimeQ[m^8+n^8]&&PrimeQ[m^16+n^16]), m++ ];m)
%e A090873 a(2)=1 because 2^2^k + 1 is prime for k= 0,1,2,3 and 4.
%t A090873 a[n_] := (For[m=1, !(PrimeQ[m+n]&&PrimeQ[m^2+n^2]&&PrimeQ[m^4+n^4]&& 
               PrimeQ[m^8+n^8]&&PrimeQ[m^16+n^16]), m++ ];m);Do[Print[a[n]], {n, 
               50}]
%Y A090873 Cf. A090872, A019434, A000215.
%Y A090873 Sequence in context: A078520 A019291 A157377 this_sequence A072189 A046396 
               A083640
%Y A090873 Adjacent sequences: A090870 A090871 A090872 this_sequence A090874 A090875 
               A090876
%K A090873 nonn
%O A090873 1,3
%A A090873 Farideh Firoozbakht (f.firoozbakht(AT)sci.ui.ac.ir), Feb 06 2004