|
| |
|
|
A102930
|
|
Numbers n such that 10^n + 2*R_n + 5 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
|
|
2
|
|
|
|
1, 2, 4, 14, 25, 32, 56, 62, 811, 812, 1084, 2533, 11924, 49552
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,2
|
|
|
COMMENTS
|
Also numbers n such that (11*10^n+43)/9 is prime.
a(15) > 10^5. - Robert Price, Jan 16 2015
|
|
|
LINKS
|
Table of n, a(n) for n=1..14.
Makoto Kamada, Prime numbers of the form 122...227.
Index entries for primes involving repunits.
|
|
|
FORMULA
|
a(n) = A102010(n) + 1.
|
|
|
MATHEMATICA
|
Do[ If[ PrimeQ[(11*10^n + 43)/9], Print[n]], {n, 0, 10000}]
|
|
|
CROSSREFS
|
Cf. A002275, A102010.
Sequence in context: A090889 A096012 A261562 * A135113 A050564 A047830
Adjacent sequences: A102927 A102928 A102929 * A102931 A102932 A102933
|
|
|
KEYWORD
|
more,nonn,changed
|
|
|
AUTHOR
|
Robert G. Wilson v, Dec 16 2004
|
|
|
EXTENSIONS
|
Addition of a(13) from Kamada data by Robert Price, Dec 12 2010
a(14) from Erik Branger May 01 2013 by Ray Chandler, Aug 16 2013
|
|
|
STATUS
|
approved
|
| |
|
|
