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A111391 Numbers n such that 10^(n+1) +(10^n-1) is a prime. 1
1, 9, 11, 17, 22, 29, 36, 37, 52, 166, 448, 2011, 3489, 4871, 6982 (list; graph; refs; listen; history; internal format)
OFFSET

1,2

MATHEMATICA

Do[ If[ PrimeQ[10^(n + 1) + (10^n - 1)], Print[n]], {n, 9500}]

CROSSREFS

Cf. A096209.

Sequence in context: A048464 A075824 A108113 * A077788 A137018 A090771

Adjacent sequences:  A111388 A111389 A111390 * A111392 A111393 A111394

KEYWORD

more,nonn

AUTHOR

Robert G. Wilson v (rgwv(AT)rgwv.com), Nov 15 2005

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Last modified February 15 08:59 EST 2012. Contains 205742 sequences.