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Search: id:A033271
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| A033271 |
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Number of odd nonprimes <= n. |
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+0
1
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| 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 6, 6, 6, 6, 6, 6, 7, 7, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 10, 10, 10, 10, 11, 11, 12, 12, 12, 12, 13, 13, 14, 14, 14, 14, 14, 14, 15, 15, 16, 16, 16, 16, 17, 17, 17, 17, 17, 17, 18, 18, 19, 19, 19, 19
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OFFSET
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1,9
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FORMULA
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If n>1, then a(n) = floor((n+1)/2) - primepi(n) + 1, where primepi denotes the number of primes <= n a(n)/n is convergent against 0.5 - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), May 09 2006
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MATHEMATICA
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Insert[Table[Floor[(n + 1)/2] - PrimePi[n] + 1, {n, 2, 80}], 1, 1] - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), May 09 2006
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CROSSREFS
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Sequence in context: A147583 A054895 A137588 this_sequence A004052 A051742 A134119
Adjacent sequences: A033268 A033269 A033270 this_sequence A033272 A033273 A033274
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
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More terms from Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), May 09 2006
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