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A208400
Smallest integer k such that k*n+1 is a prime dividing (n^n)^2 + 1.
1
8, 24, 16384, 8, 216, 1937780208, 24, 720, 167632, 22896, 8, 29256, 72, 2240, 3728099320468576, 8, 612214200, 64, 3800, 176, 40, 18624, 8, 160, 336, 19656, 280, 270006232334172274751152473116790619162839546306934626321438592627063115205009840, 8, 13392, 8568
OFFSET
2,1
EXAMPLE
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.
MATHEMATICA
Table[p=First/@FactorInteger[(n^n)^2+1]; (Select[p, Mod[#1, n] == 1 &, 1][[1]]
- 1)/n, {n, 2, 20}]
CROSSREFS
Cf. A208399.
Sequence in context: A105063 A274303 A132586 * A103953 A076444 A023056
KEYWORD
nonn
AUTHOR
Michel Lagneau, Feb 27 2012
STATUS
approved