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A117141
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Primes of the form n!!-1.
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51
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2, 7, 47, 383, 10321919, 51011754393599, 1130138339199322632554990773529330319359999999, 73562883979319395645666688474019139929848516028923903999999999
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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LINKS
| Vincenzo Librandi, Table of n, a(n) for n = 1..15
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FORMULA
| a(n) = A093173(n-1) for n>1. - Alexander Adamchuk (alex(AT)kolmogorov.com), Apr 18 2007
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EXAMPLE
| 47 = 6!! -1
383 = 8!! -1
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MAPLE
| SFACT:= proc(n) local i, j, k; for k from 1 by 1 to n do i:=k; j:=k-2; while j >0 do i:=i*j; j:=j-2; od: if isprime(i-1) then print(i-1); fi; od: end: SFACT(100);
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MATHEMATICA
| lst={}; Do[p=n!!-1; If[PrimeQ[p], AppendTo[lst, p]], {n, 0, 5!, 1}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Jan 27 2009]
Select[Table[n!!-1, {n, 1, 100}], PrimeQ] (* Vincenzo Librandi, Dec 07 2011 *)
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PROG
| (PARI) print1(2); for(n=1, 1e3, if(ispseudoprime(t=n!<<n-1), print1(", "t))) \\ Charles R Greathouse IV, Jun 16 2011
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CROSSREFS
| Cf. A002981, A002982, A088332.
Cf. A093173 = primes of the form (2^n * n!) - 1.
Sequence in context: A072287 A091117 A056854 * A125813 A106159 A160915
Adjacent sequences: A117138 A117139 A117140 * A117142 A117143 A117144
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KEYWORD
| nonn
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AUTHOR
| Paolo P. Lava & Giorgio Balzarotti (paoloplava(AT)gmail.com), Apr 21 2006
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