A082132 a(0) = 5; for n > 0, a(n) is the greatest prime factor of PP(a(n-1))*a(n-1)-2 where PP(n) is an abbreviation for PreviousPrime(n).

5, 13, 47, 673, 1093, 4789, 15887, 6961, 7079, 1853387, 5636791, 16319158451, 46975091221, 97536826417, 9513432505744326182381, 2335222008886384800739, 7440517660385876970522347503153, 83914607657246408236765553419, 1960358081272210906656999086971746456168551

Offset: 0

Author

Yasutoshi Kohmoto, May 10 2003

Keywords

• nonn

Comments

Some of the larger entries may only correspond to probable primes.

Links

• Tyler Busby, Table of n, a(n) for n = 0..22

Crossrefs

Cf. A082021, A031441, A031442.

Programs

PARI

p=5;for(k=1,20,print1(p,",");p=precprime(p-1)*p-2;f=factor(p);s=matsize(f)[1];p=f[s,1]) \\ Rick L. Shepherd, Dec 19 2004

Extensions

Edited by Rick L. Shepherd, Dec 19 2004

a(18) from Tyler Busby, Oct 22 2023