OFFSET
1,1
COMMENTS
Primes such that the leftmost digit is 4, the rightmost digit is 3, and all inner digits are 9.
LINKS
Makoto Kamada, Prime numbers of the form 499...993.
FORMULA
a(n) = 5*10^A103002(n) - 7.
MATHEMATICA
Select[Table[FromDigits[Join[PadRight[{4}, n+1, 9], {3}]], {n, 0, 150}], PrimeQ] (* Harvey P. Dale, Feb 01 2012 *)
PROG
(PARI) n10np9(n, d) = { local(x, y, k); for(x=1, n, for(k=1, 8, y=10^(x+1)*k+(10^x-1)*10+k-1; if(isprime(y), print1(y", ")) ) ) }
(Magma)[a: n in [1..250]|IsPrime(a) where a is (5*10^n-7)] // Vincenzo Librandi, Dec 11 2010
(PARI) for(n=4, 99, if(ispseudoprime(t=10^n/2-7), print1(t", "))) \\ Charles R Greathouse IV, Feb 01 2012
CROSSREFS
KEYWORD
easy,nonn,base
AUTHOR
Cino Hilliard, Jul 11 2005
EXTENSIONS
Edited by Ray Chandler, Feb 03 2012
Comments amended by Harvey P. Dale, Feb 03 2012
STATUS
approved