A243090 Pseudoprimes to base 8 that are not squarefree.

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

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