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Search: id:A124082
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| A124082 |
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Numbers n such that p(n)!/p(n)# - 1 is prime (p(i)=i-th prime). |
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+0
1
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OFFSET
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1,1
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COMMENT
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No more terms through 1000. - Ryan Propper (rpropper(AT)stanford.edu), Jan 27 2007
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EXAMPLE
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1*2*3*4*5/(2*3*5) -1 = 3 prime so a(1)=3 as 5=p(3)
1*2*3*4*5*6*7/(2*3*5*7) -1 = 23 prime so a(2)=4 as 7=p(4)
1*2*3*4*5*6*7*8*9*10*11*12*13*14*15*16*17/(2*3*5*7*11*13*17) -1 = 696729599 prime so a(3)=7 as 17=p(7)
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MATHEMATICA
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Primorial[n_] := Times @@ Select[Range[n], PrimeQ]; Do[k = Prime[n]; If[PrimeQ[k!/Primorial[k] - 1], Print[n]], {n, 10^3}] - Ryan Propper (rpropper(AT)stanford.edu), Jan 27 2007
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CROSSREFS
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Sequence in context: A117789 A113534 A030724 this_sequence A056655 A145593 A042037
Adjacent sequences: A124079 A124080 A124081 this_sequence A124083 A124084 A124085
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KEYWORD
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more,nonn
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AUTHOR
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Pierre CAMI (pierrecami(AT)tele2.fr), Nov 25 2006
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