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A157829
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Numbers n such that n!-(n-1)!+(n-2)!+1 is prime.
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0
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2, 5, 7, 11, 13, 16, 22, 29, 43, 56, 67, 83, 85, 107, 317, 325, 517
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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FORMULA
| a(n)=n!-(n-1)!+(n-2)!+1
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EXAMPLE
| a(11) = 11! - 10! + 9! + 1 = 36650881 (prime). a(16) = 16! - 15! + 14! + 1 = 19702293811201 (prime).
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MAPLE
| a := proc (n) if isprime(factorial(n-2)*((n-1)^2+1)+1) = true then n else end if end proc: seq(a(n), n = 2 .. 700); [From Emeric Deutsch (deutsch(AT)duke.poly.edu), Mar 18 2009]
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CROSSREFS
| Sequence in context: A189468 A004134 A191406 * A020581 A081259 A177512
Adjacent sequences: A157826 A157827 A157828 * A157830 A157831 A157832
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KEYWORD
| nonn
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AUTHOR
| Kyle D. Balliet (kdballie(AT)bloomu.edu), Mar 07 2009
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EXTENSIONS
| More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Mar 18 2009
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