|
|
A103080
|
|
Numbers n such that 8*10^n + 4*R_n - 1 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
|
|
1
|
|
|
0, 1, 3, 4, 10, 15, 25, 69, 159, 166, 261, 442, 1339, 1797, 2170, 3163, 3472, 4917, 18267
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,3
|
|
COMMENTS
|
Also numbers n such that (76*10^n-13)/9 is prime.
|
|
LINKS
|
|
|
FORMULA
|
|
|
MATHEMATICA
|
Do[ If[ PrimeQ[(76*10^n - 13)/9], Print[n]], {n, 0, 10000}]
|
|
CROSSREFS
|
|
|
KEYWORD
|
more,nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|