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

Author

Anders Hellström, Aug 18 2015

Keywords

• nonn
• hard
• more

Links

• Anders Hellström, Ruby program

Programs

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 *)

Extensions

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