A082132 - OEIS

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

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,1

COMMENTS

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

LINKS

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

PROG

(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

CROSSREFS

Cf. A082021, A031441, A031442.

Sequence in context: A250133 A025545 A146152 * A220900 A138277 A343549