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A102951
Numbers k such that 2*10^k + 3*R_k + 6 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
2
1, 2, 3, 4, 8, 11, 13, 24, 28, 52, 54, 94, 297, 657, 1006, 5347, 8189, 9314, 23055, 53287, 64807, 218644
OFFSET
1,2
COMMENTS
Also numbers k such that (7*10^k + 17)/3 is prime.
a(23) > 3*10^5. - Robert Price, Jul 13 2023
FORMULA
a(n) = A101956(n) + 1. - Robert Price, Nov 25 2014
MATHEMATICA
Do[ If[ PrimeQ[(7*10^n + 17)/3], Print[n]], {n, 0, 10000}]
CROSSREFS
Sequence in context: A279194 A050727 A295323 * A015935 A135909 A046812
KEYWORD
more,nonn
AUTHOR
Robert G. Wilson v, Dec 17 2004
EXTENSIONS
Addition of a(19) from Kamada data by Robert Price, Dec 10 2010
a(20)-a(21) from Kamada data by Robert Price, Nov 25 2014
a(22) from Robert Price, Jul 13 2023
STATUS
approved