A260388 a(1)=2; thereafter a(n) is the smallest prime > a(n-1) that is not a factor of any 1+A, where A is a product of one or more distinct earlier terms.

2, 5, 7, 13, 17, 29, 53, 89, 199, 271, 349, 823, 1747, 2251, 2593, 6569, 7121, 27479, 44129, 85361, 115259, 254731, 462103, 903751

Offset

1,1

Links

Table of n, a(n) for n=1..24.

Anders Hellström, Ruby program

Mathematica

L={2}; While[Length@L < 15, s= LCM@@ (1 + Times @@@ Subsets[L]); p = NextPrime@ L[[-1]]; While[ Mod[s, p] == 0, p = NextPrime@ p]; AppendTo[L, p]]; L (* inefficient, Giovanni Resta, Aug 19 2015 *)

Crossrefs

Sequence in context: A082555 A160794 A092059 * A169586 A023229 A176983

Adjacent sequences: A260385 A260386 A260387 * A260389 A260390 A260391

Keyword

nonn,hard,more

Author

Anders Hellström, Aug 18 2015

Extensions

a(14)-a(24) from Giovanni Resta, Aug 19 2015

Status

approved