OFFSET
1,3
COMMENTS
Also numbers k such that (16*10^k - 1)/3 is prime.
5*10^a(n) + 3*(10^a(n) - 1)/9 is a solution for part (b) of questions of puzzle 244 from www.primepuzzles.net. If a(n) is greater than 5812 then a(n) is an example that is asked for in this question. - Farideh Firoozbakht, Dec 02 2003
LINKS
Makoto Kamada, Prime numbers of the form 533...33.
Carlos Rivera, Puzzle 244. Null Conjunction, The Prime Puzzles and Problems Connection.
MATHEMATICA
Do[ If[ PrimeQ[ 5*10^n + 3*(10^n-1)/9], Print[n]], {n, 0, 5000}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Aug 11 2000
EXTENSIONS
1705 from Farideh Firoozbakht, Dec 18 2003
13993, 35753 and 40889 from Serge Batalov, Jan 2009 confirmed as next terms by Ray Chandler, Feb 11 2012
STATUS
approved