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A102989
Numbers n such that 4*10^n + 3*R_n + 4 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
1
1, 3, 5, 6, 8, 15, 26, 53, 60, 97, 183, 205, 302, 396, 456, 467, 607, 828, 1860, 2743, 4273, 4781, 5712, 6038, 6637, 9222, 10832, 18865, 25848, 42247, 48547, 87565, 95588
OFFSET
1,2
COMMENTS
Also numbers n such that (13*10^n+11)/3 is prime.
a(34) > 10^5. - Robert Price, May 11 2015
FORMULA
a(n) = A101724(n) + 1.
MATHEMATICA
Do[ If[ PrimeQ[(13*10^n + 11)/3], Print[n]], {n, 0, 10000}]
CROSSREFS
Sequence in context: A039869 A076210 A039014 * A005623 A335110 A152989
KEYWORD
more,nonn
AUTHOR
Robert G. Wilson v, Jan 17 2005
EXTENSIONS
Addition of a(27)-a(29) from Kamada data by Robert Price, Dec 08 2010
a(30)-a(31) from Erik Branger, May 01 2013, submitted by Ray Chandler, Aug 16 2013
a(32)-a(33) from Robert Price, May 11 2015
STATUS
approved