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A270575
Smallest composite c where exactly n composites d with d < c exist such that c^(d-1) == 1 (mod d) and d^(c-1) == 1 (mod c).
2
9, 55, 85, 259, 781, 91, 2737, 451, 645, 341, 481, 703, 4005, 4369, 4371, 2071, 7957, 8695, 561, 6697, 15251, 7107, 16705, 3201, 34133, 31609, 3277, 1105, 16589, 1891, 18705, 9881, 13833, 14701, 19345, 47197, 26335, 1729, 8321, 2821, 2701, 35371, 12801, 22177
OFFSET
1,1
COMMENTS
a(n) = smallest A002808(i) with A270573(i) = n for some i > 0.
PROG
(PARI) a(n) = forcomposite(c=1, , my(i=0); forcomposite(d=1, c-1, if(Mod(c, d)^(d-1)==1 && Mod(d, c)^(c-1)==1, i++)); if(i==n, return(c)))
CROSSREFS
Sequence in context: A157546 A157560 A157588 * A058849 A058852 A145875
KEYWORD
nonn
AUTHOR
Felix Fröhlich, Mar 19 2016
STATUS
approved