|
|
A090704
|
|
Numbers n such that n*factorial(n)-1 is prime.
|
|
3
|
|
|
2, 3, 5, 7, 8, 11, 27, 77, 98, 183, 285, 290, 397, 410, 599, 717, 731, 888, 1962, 2239, 2241, 2532, 8799, 11402
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
LINKS
|
|
|
FORMULA
|
a(n) = A049433(n)-1 because n!-(n-1)!-1 = (n-1)*(n-1)!-1.
|
|
MATHEMATICA
|
Select[Range[2600], PrimeQ[#(#!)-1]&] (* Because a(22) generates a 7524 digit number to be tested for primality, the program takes a long time to run. *) (* Harvey P. Dale, May 27 2014 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,more
|
|
AUTHOR
|
Mohammed Bouayoun (bouyao(AT)wanadoo.fr), Jan 15 2004
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|