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A102967
Numbers n such that 3*10^n + 2*R_n + 5 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
1
OFFSET
1,2
COMMENTS
Also numbers n such that (29*10^n+43)/9 is prime.
a(4) > 10^5. - Robert Price, Mar 12 2015
FORMULA
a(n) = A101830(n) + 1.
MATHEMATICA
Do[ If[ PrimeQ[(29*10^n+43)/9], Print[n]], {n, 0, 10000}]
Select[Range[5100], PrimeQ[(29 10^# + 43) / 9] &] (* Vincenzo Librandi, Mar 12 2015 *)
PROG
(Magma) [n: n in [0..1000] | IsPrime((29*10^n+43) div 9 )]; // Vincenzo Librandi, Mar 12 2015
CROSSREFS
Sequence in context: A263057 A048538 A268546 * A091545 A101630 A273628
KEYWORD
bref,more,nonn
AUTHOR
Robert G. Wilson v, Dec 17 2004
STATUS
approved