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A104146 Smallest k>0 such that n*10^k + k is prime. 1
1, 3, 1, 1, 3, 1, 1, 147, 17, 1, 3, 7, 1, 297, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

(a(n) mod 10) in {1,3,7,9}.

a(16), if it exists, is greater than 20000. - Ryan Propper, Jul 21 2006

a(16), if it exists, is greater than 42000. - Ryan Propper, Sep 25 2006

LINKS

Table of n, a(n) for n=1..15.

CROSSREFS

a(floor(A030430(n)/10)) = 1.

Sequence in context: A091840 A083985 A109848 * A193179 A133705 A046111

Adjacent sequences:  A104143 A104144 A104145 * A104147 A104148 A104149

KEYWORD

nonn,more

AUTHOR

Reinhard Zumkeller, Mar 07 2005

STATUS

approved

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Last modified April 25 13:31 EDT 2019. Contains 322461 sequences. (Running on oeis4.)