A141710 Least prime factor of n-th Carmichael number A002997(n).

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.

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

OEIS index entries for Carmichael numbers

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

Cf. A002997, A020639, A081702, A135717.

Sequence in context: A085965 A238205 A186702 * A279399 A321784 A225889

Adjacent sequences: A141707 A141708 A141709 * A141711 A141712 A141713

Keyword

nonn

Author

M. F. Hasler, Jul 01 2008

Status

approved