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Search: id:A087147
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| A087147 |
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Numbers n such that n!+(n+1)!+1 is prime. |
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3
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OFFSET
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1,2
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COMMENT
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291 is in the sequence and also is in the sequence A087146, thus (291!+292!-1,291!+292!+1) is a twin pair of primes. Any additional terms are greater than 1800 with the next prime having more than 5086 digits.
Next term is greater than 4200. - Gabriel Cunningham (gcasey(AT)mit.edu), Sep 09 2003
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REFERENCES
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H. Dubner, Factorial and primorial primes, J. Rec. Math., 19 (No.3, 1987)
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EXAMPLE
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3 is in the sequence because 3!+4!+1=31 is prime.
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MATHEMATICA
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v={}; Do[If[PrimeQ[n!+(n+1)!+1], v=Append[v, n]; Print[v]], {n, 1800}]; v
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CROSSREFS
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Cf. A087146, A051856.
Primes in A118913. [From Dmitry Kamenetsky (dkamen(AT)rsise.anu.edu.au), Oct 21 2008]
Sequence in context: A074339 A115164 A003033 this_sequence A152607 A118559 A127789
Adjacent sequences: A087144 A087145 A087146 this_sequence A087148 A087149 A087150
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KEYWORD
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more,nonn
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AUTHOR
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Farideh Firoozbakht (f.firoozbakht(AT)sci.ui.ac.ir), Aug 19 2003
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