A096101 a(1) = 1; for n > 1: a(n) = smallest number >1 such that product of any two or more successive terms - 1 is prime.

1, 3, 2, 2, 2, 3, 170, 46600, 1901907, 65157236, 42083217792, 2819475721641

Offset

1,2

Links

Table of n, a(n) for n=1..12.

Example

a(2) is not 2 since 1*2-1 = 1 is not prime, but 1*3-1 = 2 is prime, hence a(2) = 3.
a(6) is not 2 since 2*2*2*2-1 = 15 is not prime, but 2*3-1 = 5, 2*2*3-1 = 11, 2*2*2*3-1 = 23, 3*2*2*2*3-1 = 71 are all prime, hence a(6) = 3.

Crossrefs

Cf. A096100.

Sequence in context: A163751 A067279 A106267 * A104890 A064123 A024703

Adjacent sequences: A096098 A096099 A096100 * A096102 A096103 A096104

Keyword

nonn,more

Author

Amarnath Murthy, Jun 24 2004

Extensions

Edited and extended by Klaus Brockhaus, Jul 05 2004

a(10) from Donovan Johnson, Apr 22 2008

a(11)-a(12) from Bert Dobbelaere, Jan 13 2020

Status

approved