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A118744
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Primes of the form n!! + n - 1.
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0
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3, 5, 11, 19, 53, 953, 46091, 34459441, 3715891219, 6332659870762850657, 107145471557284795514880041
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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REFERENCES
| G. Balzarotti and P. P. Lava, Le sequenze di numeri interi, Hoepli, 2008, p. 159.
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EXAMPLE
| For n=2, 2!! + 2 - 1 = 2 + 2 - 1 = 3, which is prime;
for n=4, 4!! + 4 - 1 = 4*2 + 4 - 1 = 11, which is prime.
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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+k-1) then print(i+k-1); fi; od: end: SFACT(550);
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CROSSREFS
| Sequence in context: A045961 A117272 A147189 * A092672 A061068 A058932
Adjacent sequences: A118741 A118742 A118743 * A118745 A118746 A118747
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KEYWORD
| nonn,changed
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AUTHOR
| Paolo P. Lava & Giorgio Balzarotti (paoloplava(AT)gmail.com), May 22 2006
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