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A273339 Smallest composite c such that n^(c-1) =/= 1 (mod c^2), i.e., smallest composite c that is not a "Wieferich pseudoprime" to base n. 3
4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 6, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 6, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 6, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 6, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 6, 4, 4, 4, 4, 4, 4, 4 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

COMMENTS

Smallest composite c such that n does not occur in row c of the array in A244752. - Felix Fröhlich, Jan 07 2017

LINKS

Felix Fröhlich, Table of n, a(n) for n = 2..10000

PROG

(PARI) a(n) = forcomposite(c=1, , if(Mod(n, c^2)^(c-1)!=1, return(c)))

CROSSREFS

Cf. A240719, A244752, A256517, A267288, A270776.

Sequence in context: A138908 A032564 A141248 * A088899 A258199 A290205

Adjacent sequences:  A273336 A273337 A273338 * A273340 A273341 A273342

KEYWORD

nonn

AUTHOR

Felix Fröhlich, May 20 2016

STATUS

approved

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Last modified September 23 14:40 EDT 2021. Contains 347618 sequences. (Running on oeis4.)