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A031442 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). 4
13, 71, 41, 379, 23561, 5431, 20269, 89, 1231, 44497, 329952671, 36583, 1126159, 90209117, 14095897, 15272393, 13887359, 256460794943, 2740505805180429880723, 1591234463080874838018721796071210709 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Table of n, a(n) for n=0..19.

CROSSREFS

Cf. A031441.

Sequence in context: A050403 A235454 A296831 * A066831 A067382 A253776

Adjacent sequences:  A031439 A031440 A031441 * A031443 A031444 A031445

KEYWORD

nonn

AUTHOR

Yasutoshi Kohmoto

EXTENSIONS

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.

Edited by T. D. Noe, Oct 30 2008

STATUS

approved

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Last modified February 19 13:20 EST 2018. Contains 299333 sequences. (Running on oeis4.)