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A103084
Numbers n such that 8*10^n + 5*R_n - 2 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
1
1, 2, 7, 44, 56, 338, 1211, 2693, 3536, 3917, 3974, 4046, 6961, 23771, 69656
OFFSET
1,2
COMMENTS
Also numbers n such that (77*10^n-23)/9 is prime.
a(16) > 10^5. - Robert Price, Oct 22 2015
FORMULA
a(n) = A101071(n) + 1.
MATHEMATICA
Do[ If[ PrimeQ[(77*10^n - 23)/9], Print[n]], {n, 0, 10000}]
PROG
(PARI) for(n=0, 1e5, if(isprime((77*10^n-23)/9), print1(n, ", "))) \\ Altug Alkan, Oct 22 2015
CROSSREFS
Sequence in context: A212270 A270348 A270580 * A041507 A158107 A145073
KEYWORD
more,nonn
AUTHOR
Robert G. Wilson v, Jan 19 2005
EXTENSIONS
a(14) from Kamada data by Robert Price, Dec 14 2010
a(15) from Robert Price, Oct 22 2015
STATUS
approved