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A084599 a(1) = 2, a(2) = 3; for n >= 2, a(n+1) is largest prime factor of (Product_{k=1..n} a(k)) - 1. 3
2, 3, 5, 29, 79, 68729, 3739, 6221191, 157170297801581, 70724343608203457341903, 46316297682014731387158877659877, 78592684042614093322289223662773, 181891012640244955605725966274974474087, 547275580337664165337990140111772164867508038795347198579326533639132704344301831464707648235639448747816483406685904347568344407941 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Like the Euclid-Mullin sequence A000946, but subtracting rather than adding 1 to the product.

LINKS

Table of n, a(n) for n=1..14.

Dario Alpern, ECM

EXAMPLE

a(4)=29 since 2*3*5=30 and 29 is the largest prime factor of 30-1

a(5)=79 since 2*3*5*29=870 and 79 is the largest prime factor of 870-1=869=11*79.

CROSSREFS

Cf. A000946, A005265, A084598.

Essentially the same as A005266.

Sequence in context: A215103 A038962 A019400 * A062167 A279189 A107451

Adjacent sequences:  A084596 A084597 A084598 * A084600 A084601 A084602

KEYWORD

nonn

AUTHOR

Marc LeBrun, May 31 2003

EXTENSIONS

More terms from Hugo Pfoertner, May 31, 2003, using Dario Alpern's ECM.

The next term a(15) is not known. It requires the factorization of the 245-digit composite number which remains after eliminating 7 smaller factors.

STATUS

approved

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Last modified October 16 12:35 EDT 2018. Contains 316263 sequences. (Running on oeis4.)