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A103036
Numbers n such that 6*10^n + 4*R_n + 3 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
1
1, 2, 5, 10, 40, 47, 58, 73, 92, 113, 124, 130, 887, 1234, 1538, 2063, 2591, 2786, 3145, 21688, 32381, 39170, 47791, 83878
OFFSET
1,2
COMMENTS
Also numbers n such that (58*10^n+23)/9 is prime.
a(25) > 10^5. - Robert Price, Sep 15 2015
FORMULA
a(n) = A101529(n) + 1.
MATHEMATICA
Do[ If[ PrimeQ[(58*10^n + 23)/9], Print[n]], {n, 0, 10000}]
CROSSREFS
Sequence in context: A155217 A004143 A266162 * A018439 A349449 A018451
KEYWORD
more,nonn
AUTHOR
Robert G. Wilson v, Jan 18 2005
EXTENSIONS
a(20) from Kamada data by Robert Price, Dec 14 2010
a(21)-a(23) from Erik Branger May 01 2013 by Ray Chandler, Aug 16 2013
a(24) from Robert Price, Sep 15 2015
STATUS
approved