login
A102969
Numbers n such that 3*10^n + 4*R_n + 3 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
1
1, 2, 758, 1334, 2177, 4439, 5198, 6683, 35990, 47135
OFFSET
1,2
COMMENTS
Also numbers n such that (31*10^n+23)/9 is prime.
FORMULA
a(n) = A101833(n) + 1.
MATHEMATICA
Do[ If[ PrimeQ[(31*10^n+23)/9], Print[n]], {n, 0, 10000}]
CROSSREFS
Sequence in context: A252986 A247080 A145124 * A179960 A344663 A167448
KEYWORD
more,nonn
AUTHOR
Robert G. Wilson v, Dec 17 2004
EXTENSIONS
Addition of a(9) from Kamada data by Robert Price, Dec 13 2010
a(10) from Erik Branger May 01 2013 by Ray Chandler, Aug 16 2013
STATUS
approved