A102965 Numbers n such that 3*10^n + R_n + 8 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

0, 3, 143, 797, 3143, 18791, 20763, 96743

Offset

1,2

Comments

Also numbers n such that (28*10^n+71)/9 is prime.

Links

Table of n, a(n) for n=1..8.

Makoto Kamada, Prime numbers of the form 311...119.

Index entries for primes involving repunits.

Formula

a(n) = A101827(n-1) + 1.

Mathematica

Do[ If[ PrimeQ[(28*10^n+71)/9], Print[n]], {n, 0, 10000}]

Crossrefs

Cf. A002275, A101827.

Sequence in context: A279923 A195937 A162363 * A278310 A195936 A323998

Adjacent sequences: A102962 A102963 A102964 * A102966 A102967 A102968

Keyword

more,nonn

Author

Robert G. Wilson v, Dec 17 2004

Extensions

Two more PRP terms from Serge Batalov, Nov 17 2008

Addition of a(8) from Kamada data by Robert Price, Dec 13 2010

Status

approved