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%I #15 May 17 2024 03:21:29
%S 2,2,64,104,2,16,12,8,10,2,16,1032,2,2,17136,2703399548648159360,2,
%T 5700,7436,16,437174342164,2,1392,9568,2,6,16,8,2,12,20,20,176764,2,
%U 623673825204293256537467494040862720,16,5340,2,16,440,16,22,8,990520
%N a(n) is the least number k such that k*n+1 is a prime dividing n^n+1.
%C The smallest prime factor of n^n+1 of the form k*n+1 is A187022(n).
%H Amiram Eldar, <a href="/A187024/b187024.txt">Table of n, a(n) for n = 2..148</a>
%e 12^12+1 = 89*193*233*2227777; the smallest prime divisor of the form k*n+1 is 193 = 16*12+1, hence a(12)=16.
%t Table[p=First/@FactorInteger[n^n+1]; (Select[p, Mod[#1, n] == 1 &, 1][[1]]
%t - 1)/n, {n, 2, 40}]
%o (Magma) A187024:=function(n); for d in PrimeDivisors(n^n+1) do if d mod n eq 1 then return (d-1)/n; end if; end for; return 0; end function; [ A187024(n): n in [2..40] ]; // _Klaus Brockhaus_, Mar 02 2011
%Y Cf. A187022.
%K nonn
%O 2,1
%A _Michel Lagneau_, Mar 02 2011
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