OFFSET
1,1
COMMENTS
The next term is too large to include.
Values of n are 3, 5, 19, 254, 266, ... [Charles R Greathouse IV, Feb 15 2011]
The next term (a(4)) has 503 digits. - Harvey P. Dale, Jan 17 2023
EXAMPLE
n=5 -> 5!-1 = 120-1=119 -> R(119)=911 that is prime
MAPLE
P:=proc(i) local a, b, k, n, v; v:=array(1..10000); for n from 1 by 1 to i do a:=1; k:=n!-1; while k>0 do v[a]:=k-(trunc(k/10)*10); k:=trunc(k/10); a:=a+1; od; k:=0; for b from a-1 by -1 to 1 do k:=k+v[b]*10^(a-1-b); od; if isprime(k) then print(k); fi; od; end: P(2000);
MATHEMATICA
Select[IntegerReverse/@(Range[20]!-1), PrimeQ] (* Harvey P. Dale, Jan 17 2023 *)
CROSSREFS
KEYWORD
nonn,bref,base
AUTHOR
Paolo P. Lava and Giorgio Balzarotti, Mar 02 2010
STATUS
approved