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A084830
Numbers n such that (n!)^2 + n! - 1 is prime.
0
2, 3, 4, 5, 6, 14, 17, 50, 111, 254, 506
OFFSET
1,1
REFERENCES
H. Dubner, Factorial and primorial primes, J. Rec. Math., 19 (No. 3, 1987).
LINKS
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.
EXAMPLE
5 is in the sequence because (5!)^2+5!-1=14519 is prime.
MATHEMATICA
Do[If[PrimeQ[n!^2+n!-1], Print[n]], {n, 600}]
CROSSREFS
Sequence in context: A039016 A249102 A250047 * A116044 A116027 A085157
KEYWORD
more,nonn
AUTHOR
Farideh Firoozbakht, Jul 12 2003
STATUS
approved