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A102949 Numbers n such that 2*10^n + R_n + 6 is prime, where R_n = 11...1 is the repunit (A002275) of length n. 1
36, 183, 330, 393, 17520, 27222 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Also numbers n such that (19*10^n+53)/9 is prime.

a(7) > 10^5. - Robert Price, Feb 07 2015

LINKS

Table of n, a(n) for n=1..6.

Makoto Kamada, Prime numbers of the form 211...117.

Index entries for primes involving repunits.

FORMULA

a(n) = A101954(n) + 1.

MATHEMATICA

Do[ If[ PrimeQ[(19*10^n + 53)/9], Print[n]], {n, 0, 10000}]

CROSSREFS

Cf. A002275, A101954.

Sequence in context: A318100 A321145 A054979 * A211733 A211744 A211753

Adjacent sequences:  A102946 A102947 A102948 * A102950 A102951 A102952

KEYWORD

more,nonn

AUTHOR

Robert G. Wilson v, Dec 17 2004

EXTENSIONS

Addition of a(5)-a(6) from Kamada data by Robert Price, Dec 13 2010

STATUS

approved

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Last modified April 7 04:20 EDT 2020. Contains 333292 sequences. (Running on oeis4.)