A102944 - OEIS

A102944

Numbers k such that 10^k + 8*R_k - 5 is prime, where R_k = 11...1 is the repunit (A002275) of length k.

1, 16, 22, 28, 34, 90, 2068, 2374, 2854, 3720, 4242, 22666, 29292, 29508

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OFFSET

1,2

COMMENTS

Also numbers k such that (17*10^k - 53)/9 is prime.

a(15) > 10^5. - Robert Price, Feb 11 2015

LINKS

FORMULA

a(n) = A102030(n) + 1.

MATHEMATICA

Do[ If[ PrimeQ[(17*10^n - 53)/9], Print[n]], {n, 0, 10000}]

CROSSREFS

KEYWORD

more,nonn

AUTHOR

EXTENSIONS

Addition of a(12)-a(14) from Kamada data by Robert Price, Dec 12 2010

STATUS

approved