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A102966
Numbers n such that 3*10^n + 2*R_n - 1 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
1
0, 1, 3, 6, 12, 408, 649, 949, 963, 1005, 2700, 19779, 22518, 22611, 40584, 55362, 70194
OFFSET
1,3
COMMENTS
Also numbers n such that (29*10^n-11)/9 is prime.
a(18) > 10^5. - Robert Price, Apr 04 2015
FORMULA
a(n) = A101828(n-1) + 1.
MATHEMATICA
Do[ If[ PrimeQ[(29*10^n-11)/9], Print[n]], {n, 0, 10000}]
CROSSREFS
Sequence in context: A139416 A013563 A009788 * A309719 A332365 A257276
KEYWORD
more,nonn
AUTHOR
Robert G. Wilson v, Dec 17 2004
EXTENSIONS
Addition of a(12)-a(14) from Kamada data by Robert Price, Dec 13 2010
a(15) from Erik Branger May 01 2013 by Ray Chandler, Aug 16 2013
a(16)-a(17) from Robert Price, Apr 04 2015
STATUS
approved