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A099351
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Numbers k such that 5*k! - 1 is prime.
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10
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3, 5, 8, 13, 20, 25, 51, 97, 101, 241, 266, 521, 1279, 1750
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OFFSET
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1,1
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COMMENTS
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a(15) > 1879. - Jinyuan Wang, Feb 04 2020
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LINKS
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Table of n, a(n) for n=1..14.
Index entries for sequences related to numbers of primes of the form k*n!+-1
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EXAMPLE
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k = 5 is here because 5*5! - 1 = 599 is prime.
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MAPLE
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for n from 0 to 1000 do if isprime(5*n! - 1) then print(n) end if end do;
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MATHEMATICA
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Select[Range[550], PrimeQ[5#!-1]&] (* Harvey P. Dale, Nov 27 2013 *)
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PROG
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(PARI) is(n)=ispseudoprime(5*n!-1) \\ Charles R Greathouse IV, Jun 13 2017
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CROSSREFS
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Cf. A002982, A076133, A076134, A099350, A180627, A180628, A180629, A180630, A180631.
Sequence in context: A035421 A035424 A245934 * A265065 A265066 A265067
Adjacent sequences: A099348 A099349 A099350 * A099352 A099353 A099354
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KEYWORD
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nonn,more
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AUTHOR
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Brian Kell, Oct 12 2004
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EXTENSIONS
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a(13)-a(14) from Jinyuan Wang, Feb 04 2020
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STATUS
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approved
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