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A144717
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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)=2
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12
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1, 2, 3, 5, 7, 8, 9, 11, 12, 14, 17, 20, 24, 30, 34, 44, 72, 85, 86, 92, 115, 122, 125, 132, 142, 150, 161, 162, 181, 186, 198, 224, 248, 252, 282, 283, 290, 307, 319, 321, 344, 350, 376, 445, 476, 567, 623, 676, 682, 704, 741, 749, 786, 803, 806, 893, 1014, 1046
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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EXAMPLE
| a(1)=1 because 2*1+1=3 is prime a(2)=2 because 2*1*2+1=5 is prime a(3)=3 because 2*1*2*3+1=13 is prime 2*1*2*3*4+1=49 is not prime (omitted) a(4)=5 because 2*1*2*3*5+1=61 is prime
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MATHEMATICA
| k = 2; 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, 144718, A144722, A144723, A144724, A144725, A144726, A144727, A144728, A144729, A144730, A144731
Sequence in context: A156271 A186513 A158791 * A202728 A186042 A039019
Adjacent sequences: A144714 A144715 A144716 * A144718 A144719 A144720
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KEYWORD
| nonn
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AUTHOR
| Artur Jasinski (grafix(AT)csl.pl), Sep 19 2008
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