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%I #5 May 17 2014 12:43:54
%S 1,1,2,1,2,1,2,3,2,7,2,13,4,5,8,1,2,5,2,1,10,15,2,1,6,3,2,1,12,7,12,5,
%T 14,1,6,7,2,3,14,9,2,5,10,21,2,1,4,1,2,7,2,11,6,1,14,1,2,7,2,11,2,11,
%U 8,23,16,29,12,3,10,27,2,5,8,1,8,3,20,17,2,1,10,1,10
%N Least number k such that n^4+k^4 is prime.
%C If a(n) = 1, then n is in A000068.
%e 8^4+1^4 = 4097 is not prime. 8^4+2^4 = 4112 is not prime. 8^4+3^4 = 4177 is prime. Thus, a(8) = 3.
%o (Python)
%o import sympy
%o from sympy import isprime
%o def a(n):
%o ..for k in range(10**4):
%o ....if isprime(n**4+k**4):
%o ......return k
%o n = 1
%o while n < 100:
%o ..print(a(n))
%o ..n += 1
%o (PARI) a(n)=for(k=1,10^3,if(ispseudoprime(n^4+k^4),return(k)));
%o n=1;while(n<100,print(a(n));n+=1)
%Y Cf. A069003, A000068.
%K nonn
%O 1,3
%A _Derek Orr_, May 17 2014
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