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%I #14 Sep 26 2023 20:26:21
%S 13,71,41,379,23561,5431,20269,89,1231,44497,329952671,36583,1126159,
%T 90209117,14095897,15272393,13887359,256460794943,
%U 2740505805180429880723,1591234463080874838018721796071210709
%N a(0) = 13; for n > 0, a(n) is the greatest prime factor of PreviousPrime(a(n-1))*a(n-1)-1 where PreviousPrime(prime(k))=prime(k-1).
%H Tyler Busby, <a href="/A031442/b031442.txt">Table of n, a(n) for n = 0..21</a>
%Y Cf. A031441.
%K nonn
%O 0,1
%A _Yasutoshi Kohmoto_
%E More terms from Kok Seng Chua (chuaks(AT)ihpc.nus.edu.sg), May 23 2000. a(19) and a(20) pass the strong pseudoprime test for many bases.
%E Edited by _T. D. Noe_, Oct 30 2008