

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, 85964
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OFFSET

1,2


COMMENTS

Also numbers n such that (32*10^n+31)/9 is prime.
a(19) > 10^5.  Robert Price, May 31 2015


LINKS

Table of n, a(n) for n=1..18.
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
a(18) from Robert Price, May 31 2015


STATUS

approved



