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Search: id:A117141
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| A117141 |
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Primes of the form n!!-1. |
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+0
52
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| 2, 7, 47, 383, 10321919, 51011754393599, 1130138339199322632554990773529330319359999999, 73562883979319395645666688474019139929848516028923903999999999
(list; graph; listen)
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OFFSET
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1,1
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FORMULA
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a(n) = A093173(n-1) for n>1. - Alexander Adamchuk (alex(AT)kolmogorov.com), Apr 18 2007
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EXAMPLE
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47 = 6!! -1
383 = 8!! -1
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MAPLE
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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
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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]
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CROSSREFS
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Cf. A002981, A002982, A088332.
Cf. A093173 = primes of the form (2^n * n!) - 1.
Sequence in context: A072287 A091117 A056854 this_sequence A125813 A106159 A160915
Adjacent sequences: A117138 A117139 A117140 this_sequence A117142 A117143 A117144
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KEYWORD
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nonn
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AUTHOR
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Paolo P. Lava & Giorgio Balzarotti (ppl(AT)spl.at), Apr 21 2006
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