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A118769
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Primes of the form n! - n!! + 1.
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1
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17, 673, 39937, 87177646081, 6402373519933441, 304888344611712432172380979201, 126886932185884164103433389335161480802865515044406852999479261820223930701069680640000001
(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=4, 4! - 4!! + 1 = 4*3*2*1 - 4*2 + 1 = 24 - 8 + 1 = 17, 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(k!-i+1) then print(k!-i+1); fi; od: end: SFACT(300);
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CROSSREFS
| Sequence in context: A203170 A063941 A089018 * A009158 A012050 A012157
Adjacent sequences: A118766 A118767 A118768 * A118770 A118771 A118772
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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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