A219346 Pseudoprimes to base 2 that are divisible by the squares of at least two primes.

4578627124156945861, 57406119388190085241, 71879404939979986441, 98654983210791303661, 109509947374633729561, 153653468307592928221, 213717603347521018201, 541537521095562280381, 608114634633795825901, 721729926215346550321, 1062575800959998723581

Offset: 1

Author

Charles R Greathouse IV, Nov 18 2012

Keywords

• nonn

Comments

2-pseudoprimes of the form n*p^2*q^2, where p and q are distinct Wieferich primes (A001220).

Unless there are other Wieferich primes besides 1093 and 3511, the sequence is the intersection of A247830 and A247831. - Max Alekseyev, Nov 26 2017

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Crossrefs

Subsequence of each of the following sequences: A158358, A247830, A247831.

Programs

PARI

forstep(n=236641458619975501,4.489e31,723664277589495060,if(Mod(2,n)^(n-1)==1, print1(n", ")))