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

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

Table of n, a(n) for n=1..14.

Makoto Kamada, Prime numbers of the form 188...883.

Index entries for primes involving repunits.

Formula

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

Mathematica

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

Crossrefs

Cf. A002275, A102030.

Sequence in context: A360735 A341169 A064804 * A058901 A059756 A242214

Adjacent sequences: A102941 A102942 A102943 * A102945 A102946 A102947

Keyword

more,nonn

Author

Robert G. Wilson v, Dec 16 2004

Extensions

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

Status

approved