A102982 Numbers n such that 4*10^n + R_n + 6 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

1, 4, 84, 165, 274, 513, 3372, 4177, 4318, 10579, 17221, 19672, 20065, 36646, 40191, 55359, 86230

Offset

1,2

Comments

Also numbers n such that (37*10^n+53)/9 is prime.

a(18) > 10^5. - Robert Price, May 10 2015

Links

Table of n, a(n) for n=1..17.

Makoto Kamada, Prime numbers of the form 411...117.

Index entries for primes involving repunits.

Formula

a(n) = A101717(n) + 1.

Mathematica

Do[ If[ PrimeQ[(37*10^n + 53)/9], Print[n]], {n, 0, 10000}]

Crossrefs

Cf. A002275, A101717.

Sequence in context: A333458 A119514 A316490 * A231741 A359861 A172138

Adjacent sequences: A102979 A102980 A102981 * A102983 A102984 A102985

Keyword

more,nonn

Author

Robert G. Wilson v, Dec 21 2004

Extensions

Addition of a(10)-a(13) from Kamada data by Robert Price, Dec 13 2010

a(14)-a(15) from Erik Branger May 01 2013 by Ray Chandler, Aug 16 2013

a(16)-a(17) from Robert Price, May 10 2015

Status

approved