OFFSET
1,1
COMMENTS
Prime versus probable prime status and proofs are given in the author's table.
a(13) > 2*10^5. - Tyler Busby, Feb 01 2023
REFERENCES
C. Caldwell and H. Dubner, "Journal of Recreational Mathematics", Volume 28, No. 1, 1996-97, pp. 1-9.
LINKS
Patrick De Geest, PDP Reference Table - 727.
Makoto Kamada, Prime numbers of the form 722...227.
FORMULA
a(n) = A056257(n) + 2.
EXAMPLE
k=9 -> (65*10^(9-1) + 43)/9 = 722222227.
CROSSREFS
KEYWORD
nonn,base,hard,more
AUTHOR
Patrick De Geest, Apr 13 2003
EXTENSIONS
Update from De Geest site by Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
a(11)=51779 from Ray Chandler, Nov 16 2010
Edited by Ray Chandler, Nov 05 2014
a(12) from Tyler Busby, Feb 01 2023
STATUS
approved