OFFSET
1,2
COMMENTS
Also, numbers k such that (7*10^k + 83)/9 is prime.
Terms from Kamada. Note Kamada does not recognize k=1 as 17 is a degenerate case of form AAA..ABA.
a(17) > 30000.
a(19) > 2*10^5. - Tyler Busby, Feb 01 2023
LINKS
EXAMPLE
For k=3, 7*R_11 + 10 = 777 + 10 = 787 which is prime.
MATHEMATICA
Select[Range[0, 30000], PrimeQ[(7*10^# + 83)/9] &]
CROSSREFS
KEYWORD
more,hard,nonn
AUTHOR
Robert Price, Apr 12 2015
EXTENSIONS
a(17)-a(18) from Tyler Busby, Feb 01 2023
STATUS
approved