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 A208400 Smallest integer k such that k*n+1 is a prime dividing (n^n)^2 + 1. 1

%I

%S 8,24,16384,8,216,1937780208,24,720,167632,22896,8,29256,72,2240,

%T 3728099320468576,8,612214200,64,3800,176,40,18624,8,160,336,19656,

%U 280,270006232334172274751152473116790619162839546306934626321438592627063115205009840,8,13392,8568

%N Smallest integer k such that k*n+1 is a prime dividing (n^n)^2 + 1.

%e a(3) = 24 because (3^3)^2 + 1 =2*5*73 and the smallest prime divisor of the form k*n+1 is 73 = 24*3+1 => k = 24.

%t Table[p=First/@FactorInteger[(n^n)^2+1]; (Select[p, Mod[#1, n] == 1 &, 1][[1]]

%t - 1)/n, {n, 2, 20}]

%Y Cf. A208399.

%K nonn

%O 2,1

%A _Michel Lagneau_, Feb 27 2012

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Last modified August 18 21:45 EDT 2022. Contains 356215 sequences. (Running on oeis4.)