A102969 Numbers n such that 3*10^n + 4*R_n + 3 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

1, 2, 758, 1334, 2177, 4439, 5198, 6683, 35990, 47135

Offset

1,2

Comments

Also numbers n such that (31*10^n+23)/9 is prime.

Links

Table of n, a(n) for n=1..10.

Makoto Kamada, Prime numbers of the form 344...447.

Index entries for primes involving repunits.

Formula

a(n) = A101833(n) + 1.

Mathematica

Do[ If[ PrimeQ[(31*10^n+23)/9], Print[n]], {n, 0, 10000}]

Crossrefs

Cf. A002275, A101833.

Sequence in context: A252986 A247080 A145124 * A179960 A344663 A167448

Adjacent sequences: A102966 A102967 A102968 * A102970 A102971 A102972

Keyword

more,nonn

Author

Robert G. Wilson v, Dec 17 2004

Extensions

Addition of a(9) from Kamada data by Robert Price, Dec 13 2010

a(10) from Erik Branger May 01 2013 by Ray Chandler, Aug 16 2013

Status

approved