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A102948 Numbers n such that 2*10^n + R_n + 2 is prime, where R_n = 11...1 is the repunit (A002275) of length n. +0
2
1, 3, 7, 13, 24, 30, 48, 52, 163, 175, 219, 228, 261, 754, 951, 1344, 1573, 3294, 3523 (list; graph; listen)
OFFSET

1,2

COMMENT

Also numbers n such that (19*10^n+17)/9 is prime.

LINKS

Makoto Kamada, Factorizations of 211...113.

Index entries for primes involving repunits.

MATHEMATICA

Do[ If[ PrimeQ[(19*10^n + 17)/9], Print[n]], {n, 0, 10000}]

CROSSREFS

Sequence in context: A147380 A146606 A101302 this_sequence A061263 A156209 A076276

Adjacent sequences: A102945 A102946 A102947 this_sequence A102949 A102950 A102951

KEYWORD

more,nonn

AUTHOR

Robert G. Wilson v (rgwv(AT)rgwv.com), Dec 17 2004

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Last modified November 27 22:38 EST 2009. Contains 167602 sequences.


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