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A102998
Numbers n such that 4*10^n + 8*R_n - 5 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
1
1, 4, 10, 12, 13, 40, 76, 123, 501, 648, 3541, 4002, 4228, 5271, 7432, 27306, 43402
OFFSET
1,2
COMMENTS
Also numbers n such that (44*10^n-53)/9 is prime.
a(18) > 10^5. - Robert Price, Jun 01 2015
FORMULA
a(n) = A101735(n) + 1.
MATHEMATICA
Do[ If[ PrimeQ[(44*10^n - 53)/9], Print[n]], {n, 0, 10000}]
CROSSREFS
Sequence in context: A355275 A092428 A170943 * A071179 A155475 A023693
KEYWORD
more,nonn
AUTHOR
Robert G. Wilson v, Jan 17 2005
EXTENSIONS
Addition of a(16) from Kamada data by Robert Price, Dec 12 2010
a(17) from Erik Branger, May 01 2013, submitted by Ray Chandler, Aug 16 2013
STATUS
approved