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Search: id:A104564
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| A104564 |
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Number of distinct prime divisors of 77...771 (with n 7s). |
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+0
6
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| 1, 2, 2, 2, 3, 2, 2, 2, 2, 3, 3, 1, 3, 4, 2, 2, 3, 2, 1, 4, 3, 1, 3, 3, 2, 3, 4, 2, 7, 1, 5, 6, 3, 3, 4, 3, 4, 5, 5, 3, 5, 4, 2, 3, 3, 6, 2, 2, 6, 5
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OFFSET
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0,2
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COMMENT
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Also numbers n such that 10^(n + 1) - 1)*7/9 - 6 is prime. - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Mar 01 2006
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EXAMPLE
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The number of distinct prime divisors of 71 is 1 (prime).
The number of distinct prime divisors of 771 is 2.
The number of distinct prime divisors of 7771 is 2.
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MATHEMATICA
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Table[Length[FactorInteger[(10^(n + 1) - 1)*7/9 - 6]], {n, 1, 50}] - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Mar 01 2006
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CROSSREFS
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Cf. A104484, A104483.
Cf. A104484 [3 instead of 7], A104659 [4 instead of 7], A104517 [5 instead of 7], A104890 [6 instead of 7], A105972 [8 instead of 7], A105259 [9 instead of 7].
Sequence in context: A071137 A089367 A130192 this_sequence A064656 A056608 A091787
Adjacent sequences: A104561 A104562 A104563 this_sequence A104565 A104566 A104567
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KEYWORD
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nonn,base
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AUTHOR
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Parthasarathy Nambi (PachaNambi(AT)yahoo.com), Apr 20 2005
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EXTENSIONS
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More terms from Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Mar 01 2006
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