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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 (list; graph; refs; listen; history; text; internal format)
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, Factorizations of 355...559.

Index entries for primes involving repunits.

MATHEMATICA

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

CROSSREFS

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

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Last modified November 22 23:24 EST 2014. Contains 249835 sequences.