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A103037
Numbers n such that 6*10^n + 4*R_n + 5 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
1
0, 3, 105, 627, 687, 699, 5715, 11391, 11673
OFFSET
1,2
COMMENTS
Also numbers n such that (58*10^n+41)/9 is prime.
a(10) > 10^5. - Robert Price, Sep 11 2015
FORMULA
a(n) = A101530(n-1) + 1 for n>1.
EXAMPLE
For n=0, (58*10^n+41)/9=11 which is prime, so 0 is in the sequence.
MATHEMATICA
Do[ If[ PrimeQ[(58*10^n + 41)/9], Print[n]], {n, 0, 10000}]
CROSSREFS
Sequence in context: A050651 A233251 A279303 * A228309 A215945 A350986
KEYWORD
more,nonn
AUTHOR
Robert G. Wilson v, Jan 18 2005
EXTENSIONS
a(8)-a(9) from Kamada data by Robert Price, Dec 14 2010
Inserted a(1)=0 by Robert Price, Sep 11 2015
STATUS
approved