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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
2, 5, 7, 13, 17, 29, 53, 89, 199, 271, 349, 823, 1747, 2251, 2593, 6569, 7121, 27479, 44129, 85361, 115259, 254731, 462103, 903751 (list; graph; refs; listen; history; text; internal format)
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

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Last modified May 12 10:17 EDT 2021. Contains 343821 sequences. (Running on oeis4.)