A243089 Pseudoprimes to base 7 that are not squarefree.

25, 325, 1825, 4525, 4825, 10225, 12025, 16725, 20425, 30025, 35425, 58825, 177025, 216525, 265525, 352225, 526825, 611425, 675925, 710425, 717025, 746425, 772525, 784225, 834025, 877825, 1125825, 1126225, 1439425, 1491025, 1579225, 1935025, 1973425, 2176525

Offset: 1

Author

Felix Fröhlich, Aug 18 2014

Keywords

• nonn

Comments

Any term is divisible by the square of a base 7 Wieferich prime (A123693).

Intersection of A005938 and A013929. - Michel Marcus, Aug 21 2014

Links

• Amiram Eldar, Table of n, a(n) for n = 1..3095 (terms below 10^12)

Crossrefs

Cf. A005938, A123693, A158358, A243010, A243090, A244065.

Programs

PARI

forcomposite(n=1, 1e9, if(Mod(7, n)^(n-1)==1, if(!issquarefree(n), print1(n, ", "))))