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A103044
Numbers n such that 6*10^n + 8*R_n - 7 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
1
1, 4, 10, 13, 178, 304, 331, 502, 744, 1027, 1770, 5305, 55075
OFFSET
1,2
COMMENTS
Also numbers n such that (62*10^n-71)/9 is prime.
a(14) > 10^5. - Robert Price, Sep 15 2015
FORMULA
a(n) = A101537(n) + 1.
MATHEMATICA
Do[ If[ PrimeQ[(62*10^n - 71)/9], Print[n]], {n, 0, 10000}]
CROSSREFS
Sequence in context: A032821 A101576 A179134 * A310360 A114719 A116954
KEYWORD
more,nonn
AUTHOR
Robert G. Wilson v, Jan 18 2005
EXTENSIONS
a(13) from Robert Price, Sep 15 2015
STATUS
approved