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A146170
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Percentage (rounded) of odd numbers < 2^n which are primes or squarefree semiprimes.
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0
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0, 50, 75, 75, 75, 78, 78, 77, 75, 72, 70, 66, 64, 61, 59, 57, 55, 53, 51, 49, 48, 46, 45, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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FORMULA
| a(n) = round((A146168(n)+A007053(n)-1)/(2^(n-1))*100).
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EXAMPLE
| a(4)=75 because 75% of the 2^3 numbers 1, 3, 5, 7, 9, 11, 13 and 15 are primes or squarefree semiprimes.
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CROSSREFS
| Cf. A001358(semiprimes), A007053(Number of primes <= 2^n), A146168(Number of odd squarefree semiprimes < 2^n).
Sequence in context: A180103 A102803 A039473 * A071366 A045165 A138381
Adjacent sequences: A146167 A146168 A146169 * A146171 A146172 A146173
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KEYWORD
| nonn
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AUTHOR
| W. Bomfim (webonfim(AT)bol.com.br), Oct 27 2008
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