|
| |
|
|
A202424
|
|
Primes of the form n!*n!! - 1.
|
|
1
|
|
|
|
3, 17, 191, 13934591999, 414935135999, 841488455807999, 12256784251917004799999, 91886617089132974573617151999999, 20572604964026488636856632501862399999999, 624332713268595066448813603451600045741761894966886399999999999
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,1
|
|
|
COMMENTS
|
For n > 4, the last digits of the prime numbers are of the form 999, 999, 99999, 999999,...,...99999.
|
|
|
LINKS
|
Table of n, a(n) for n=1..10.
|
|
|
EXAMPLE
|
191 is in the sequence because, for n = 4, 4!*4!! - 1 = 24*8 - 1 = 191.
|
|
|
MATHEMATICA
|
a={}; Do[p=n!*n!!-1; If[PrimeQ[p], AppendTo[a, p]], {n, 10^3}]; Print[a];
|
|
|
PROG
|
(MAGMA) a:=func< n | Factorial(n)*(&*[n..2 by -2])-1 >; [ a(n): n in [0..78] | IsPrime(a(n)) ]; // Bruno Berselli, Dec 19 2011
|
|
|
CROSSREFS
|
Cf. A000142, A006882, A202426.
Sequence in context: A088678 A195067 A158885 * A335343 A133991 A210898
Adjacent sequences: A202421 A202422 A202423 * A202425 A202426 A202427
|
|
|
KEYWORD
|
nonn
|
|
|
AUTHOR
|
Michel Lagneau, Dec 19 2011
|
|
|
STATUS
|
approved
|
| |
|
|
