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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
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OFFSET
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1,1
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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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LINKS
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Table of n, a(n) for n=1..11.
Dorin Andrica, George C. Ţurkaş, An elliptic Diophantine equation from the study of partitions, Stud. Univ. Babeş-Bolyai Math. (2019) Vol. 64, No. 3, 349-356.
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EXAMPLE
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5 is in the sequence because (5!)^2+5!-1=14519 is prime.
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MATHEMATICA
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Do[If[PrimeQ[n!^2+n!-1], Print[n]], {n, 600}]
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CROSSREFS
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Cf. A002981, A002982.
Sequence in context: A039016 A249102 A250047 * A116044 A116027 A085157
Adjacent sequences: A084827 A084828 A084829 * A084831 A084832 A084833
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KEYWORD
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more,nonn
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AUTHOR
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Farideh Firoozbakht, Jul 12 2003
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STATUS
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approved
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