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Search: id:A116898
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| A116898 |
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Numbers n such that n! is turned into a prime number by changing its trailing 0's into 1's. |
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+0
1
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OFFSET
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1,1
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COMMENT
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Also numbers n such that n!+R(Z(n)) is prime, where R(t)=(10^t-1)/9 is the repunit with t digits (A002275) and Z(m)=Sum_{j=1,..} floor(m/5^k) is the number of trailing zeros of m! (A027868). The (probable) prime corresponding to a(5)=1746 has 4905 digits. Next term must be greater than 4000.
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EXAMPLE
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10 is a term, since 10!=3628800 and 3628811 is prime.
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CROSSREFS
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Cf. A000142, A002275, A027868.
Sequence in context: A124634 A052965 A108924 this_sequence A033261 A100230 A135963
Adjacent sequences: A116895 A116896 A116897 this_sequence A116899 A116900 A116901
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KEYWORD
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hard,more,nonn
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AUTHOR
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Giovanni Resta (g.resta(AT)iit.cnr.it), Mar 07 2006
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