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A118812
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Primes of the form (2n)! - n! + 1.
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8
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OFFSET
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1,1
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COMMENTS
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The next term, if it exists, has more than 7500 digits. - M. F. Hasler, Feb 09 2014
Primes in sequence A237580 = n -> (2n)! - n! + 1, i.e., the terms of that sequence which coincide with A237579(n) = least prime factor of (2n)! - n! + 1. - M. F. Hasler, Feb 09 2014
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REFERENCES
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G. Balzarotti and P. P. Lava, Le sequenze di numeri interi, Hoepli, 2008, p. 159.
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LINKS
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FORMULA
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EXAMPLE
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For n=2, (2*2)! - 2! + 1 = 24 - 2 + 1 = 23, which is prime.
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MAPLE
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PFACT:=proc(N) local i, r; for i from 1 by 1 to N do r:=(2*i)!-i!+1; if isprime(r) then print(i); fi; od; end: PFACT(100);
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MATHEMATICA
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Select[Table[(2n)!-n!+1, {n, 30}], PrimeQ] (* Harvey P. Dale, May 05 2018 *)
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PROG
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(PARI) for(n=1, 999, ispseudoprime(p=(2*n)!-n!+1)&&print1(p", ")) \\ M. F. Hasler, Feb 09 2014
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CROSSREFS
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Cf. A237443 (corresponding values of n).
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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