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A084830
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Numbers n such that (n!)^2 + n! - 1 is prime.
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0
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2, 3, 4, 5, 6, 14, 17, 50, 111, 254, 506
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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REFERENCES
| H. Dubner, Factorial and primorial primes, J. Rec. Math., 19 (No. 3, 1987).
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EXAMPLE
| 5 is in the sequence because (5!)^2+5!-1=14519 is prime.
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MATHEMATICA
| Do[If[PrimeQ[n!^2+n!-1], Print[n]], {n, 600}]
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CROSSREFS
| Cf. A002981, A002982.
Sequence in context: A065638 A204896 A039016 * A116044 A116027 A085157
Adjacent sequences: A084827 A084828 A084829 * A084831 A084832 A084833
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KEYWORD
| more,nonn
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AUTHOR
| Farideh Firoozbakht (f.firoozbakht(AT)sci.ui.ac.ir), Jul 12 2003
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