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A144722
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a(n)= smallest positive integer k such that a(0)*a(1)*a(2)*...*a(n) + 1 is prime. a(0)=3
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13
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2, 3, 4, 6, 8, 21, 23, 26, 30, 36, 37, 39, 42, 54, 57, 73, 83, 86, 88, 91, 93, 98, 99, 112, 120, 137, 140, 142, 148, 161, 162, 169, 171, 174, 179, 237, 247, 294, 312, 335, 340, 382, 474, 475, 484, 498, 500, 539, 589, 598, 653, 654, 660, 704, 720, 732, 789, 804
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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EXAMPLE
| 3*1+1=4 is not prime (omitted) a(1)=2 because 3*2+1=7 is prime a(2)=3 because 3*2*3+1=19 is prime
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MATHEMATICA
| k = 3; a = {}; Do[If[PrimeQ[k n + 1], k = k n; AppendTo[a, n]], {n, 1, 3000}]; a (*Artur Jasinski*)
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CROSSREFS
| A046966, A046972, A144717, A144718, A144722, A144723, A144724, A144725, A144726, A144727, A144728, A144729, A144730, A144731
Sequence in context: A111023 A008324 A084074 * A105808 A124058 A118080
Adjacent sequences: A144719 A144720 A144721 * A144723 A144724 A144725
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KEYWORD
| nonn
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AUTHOR
| Artur Jasinski (grafix(AT)csl.pl), Sep 19 2008
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