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A243090 Pseudoprimes to base 8 that are not squarefree. 5
9, 45, 63, 117, 153, 585, 2169, 4005, 9945, 13833, 17865, 27261, 33201, 36873, 40833, 57681, 69345, 69921, 95085, 140985, 155961, 161721, 171405, 186201, 189441, 192465, 203841, 240471, 242451, 244413, 316881, 321201, 406341, 481041, 482769, 488709, 501921 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Any member of the sequence is divisible by the square of a base 8 Wieferich prime, of which only three cases are known, namely 3, 1093 and 3511.

Intersection of A020137 and A013929. - Michel Marcus, Aug 21 2014

LINKS

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

PROG

(PARI) forcomposite(n=1, 1e9, if(Mod(8, n)^(n-1)==1, if(!issquarefree(n), print1(n, ", "))))

CROSSREFS

Cf. A020137, A158358, A243010, A243089, A244065.

Sequence in context: A045913 A044492 A207359 * A067536 A139609 A321779

Adjacent sequences:  A243087 A243088 A243089 * A243091 A243092 A243093

KEYWORD

nonn

AUTHOR

Felix Fröhlich, Aug 18 2014

STATUS

approved

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Last modified August 5 07:54 EDT 2021. Contains 346464 sequences. (Running on oeis4.)