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%I #9 Jul 26 2013 11:25:22
%S 0,1,1,2,1,6,1,16,9,2,1,2,1,6,5,22,1,8,1,10,3,2,1,2,17,12,3,4,1,2,1,6,
%T 5,4,3,2,1,4,5,2,1,6,1,4,23,2,1,24,5,4,3,2,1,2,5,6,3,28,1,8,1,22,39,2,
%U 3,2,1,4,5,2,1,2,1,6,9,34,7,6,1,10,3,16,1,2,23,22,3,14,1,14,23,12,9,4,3,2,1,4,9,2,1,2,1,4,5,2,1,8,1,4,3,2,1,2,23,12,5,40,31,92,7
%N Least k>0 such that k^7+n is prime, or 0 if there is no such k.
%C See A225768 for motivation and references.
%o (PARI) (a,b=5)->{#factor(x^b+a)~==1&for(n=1,9e9,ispseudoprime(n^b+a)&return(n));a==1 || print1("/*"factor(x^b+a)"*/")} \\ For illustrative purpose only. The polynomial is factored to avoid an infinite search loop when it is composite. But a factored polynomial can yield a prime when all factors but one equal 1. This happens for b=4, n=4, cf. A225766.
%Y See A085099, A225765--A225770 for the k^2, k^3, ..., k^8 analogs.
%K nonn
%O 0,4
%A _M. F. Hasler_, Jul 25 2013
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