

A102973


Numbers n such that 3*10^n + 5*R_n + 4 is prime, where R_n = 11...1 is the repunit (A002275) of length n.


1



0, 2, 3, 5, 8, 14, 77, 195, 218, 957, 1052, 1163, 1485, 1731, 1970, 3237, 17354
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OFFSET

1,2


COMMENTS

Also numbers n such that (32*10^n+31)/9 is prime.


LINKS

Table of n, a(n) for n=1..17.
Makoto Kamada, Prime numbers of the form 355...559.
Index entries for primes involving repunits.


FORMULA

a(n) = A101838(n1) + 1.


MATHEMATICA

Do[ If[ PrimeQ[(32*10^n+31)/9], Print[n]], {n, 0, 10000}]


CROSSREFS

Cf. A002275, A101838.
Sequence in context: A196118 A104880 A152478 * A066372 A058519 A181065
Adjacent sequences: A102970 A102971 A102972 * A102974 A102975 A102976


KEYWORD

more,nonn


AUTHOR

Robert G. Wilson v, Dec 17 2004


EXTENSIONS

Addition of a(17) from Kamada data by Robert Price, Dec 12 2010


STATUS

approved



