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A112386 Smallest prime obtained by appending one or more 1's to n. 1
11, 211, 31, 41, 511111, 61, 71, 811, 911, 101, 1111111111111111111, 121111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111, 131, 14111111111, 151, 16111, 1711111111, 181, 191, 2011, 211, 22111, 2311, 241 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

Number of appended ones: 1,2,1,1,5,1,1,2,2,1,17,1,1,2,7,1,2,1,1,2,2,67,2,4,217,3,2,1,6,1,.., . - Robert G. Wilson v, Dec 05 2005

EXAMPLE

a(5) = 511111 because 51, 511, 5111 and 51111 are not primes.

MATHEMATICA

f[n_] := Block[{k = 1, e = Floor[Log[10, n] + 1]}, While[ !PrimeQ[n*10^k + (10^k - 1)/9], k++ ]; n*10^k + (10^k - 1)/9]; Array[f, 24] (* Robert G. Wilson v *)

CROSSREFS

Sequence in context: A060496 A157691 A196944 * A160693 A167442 A124991

Adjacent sequences:  A112383 A112384 A112385 * A112387 A112388 A112389

KEYWORD

nonn,base

AUTHOR

Michel Dauchez (mdzdm(AT)yahoo.fr), Dec 04 2005

EXTENSIONS

Edited, corrected and extended by Robert G. Wilson v (rgwv(at)rgwv.com), Dec 05 2005

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Last modified February 14 23:53 EST 2012. Contains 205689 sequences.