A020239 - OEIS

%I #23 Jan 21 2026 04:29:30

%S 85,1099,5149,7107,8911,9637,13019,14491,17803,19757,20881,22177,

%T 23521,26521,35371,44173,45629,54097,56033,57205,75241,83333,85285,

%U 86347,102719,110309,153401,184339,191959,222529,242845,253021,253927,269861

%N Strong pseudoprimes to base 13.

%H Amiram Eldar, <a href="/A020239/b020239.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..668 from R. J. Mathar)

%H <a href="/index/Ps#pseudoprimes">Index entries for sequences related to pseudoprimes</a>.

%o (PARI) /* insert A001262 code here */

%o isA020239(n)={

%o         isStrongPsp(n,13)

%o }

%o {

%o for(n=1,10000000000, if(isA020239(n), print(n) ;) ;) ;

%o } /* _R. J. Mathar_, Mar 07 2012 */

%Y Superset of A188755.

%Y Subsequence of A020141.

%K nonn

%O 1,1

%A _David W. Wilson_