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A141710
Least prime factor of n-th Carmichael number A002997(n).
5
3, 5, 7, 5, 7, 7, 7, 5, 7, 13, 7, 13, 7, 3, 7, 11, 7, 13, 7, 17, 7, 7, 41, 5, 37, 13, 19, 13, 31, 41, 5, 37, 31, 13, 13, 3, 11, 7, 7, 5, 7, 11, 7, 19, 7, 5, 7, 43, 31, 37, 17, 23, 7, 31, 41, 11, 19, 17, 13, 53, 5, 7, 11, 43, 13, 5, 29, 5, 101, 53, 7, 13, 11, 7, 19, 31, 41, 13, 29, 31, 5
OFFSET
1,1
COMMENTS
All terms of this sequence are odd primes. See A002997 for references.
FORMULA
a(n) = A020639(A002997(n))
EXAMPLE
a(1)=3 since A002997(1)=3*11*17.
MATHEMATICA
CarmichaelQ[n_] := Not[PrimeQ[n]] && Divisible[n - 1, CarmichaelLambda[n]]; FactorInteger[#][[1, 1]]& /@ Select[Range[4, 10^7], CarmichaelQ] (* Jean-François Alcover, Sep 23 2011 *)
PROG
(PARI) A141710(n)=vecmin(factor(A002997(n))[, 1]) /* where A002997(n) can be defined as follows: */ system("wget b002997.txt; sed -e 's/^[0-9]*//' <b002997.txt >b002997.gp"); A2997=readvec("b002997.gp"); A002997(n)=A2997[n]; \
CROSSREFS
KEYWORD
nonn
AUTHOR
M. F. Hasler, Jul 01 2008
STATUS
approved