|
|
A187022
|
|
a(n) is the smallest prime factor of n^n+1 having the form k*n+1.
|
|
5
|
|
|
5, 7, 257, 521, 13, 113, 97, 73, 101, 23, 193, 13417, 29, 31, 274177, 45957792327018709121, 37, 108301, 148721, 337, 9617835527609, 47, 33409, 239201, 53, 163, 449, 233, 61, 373, 641, 661, 6009977, 71, 22452257707354557235348829785471057921, 593, 202921, 79, 641
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
2,1
|
|
COMMENTS
|
|
|
LINKS
|
|
|
EXAMPLE
|
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)=193.
|
|
MATHEMATICA
|
Table[p=First/@FactorInteger[n^n+1]; Select[p, Mod[#1, n] == 1 &, 1][[1]], {n, 2, 40}]
|
|
PROG
|
(Magma) A187022:=function(n); for d in PrimeDivisors(n^n+1) do if d mod n eq 1 then return d; end if; end for; return 0; end function; [ A187022(n): n in [2..40] ]; // Klaus Brockhaus, Mar 02 2011
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|