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A066854
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a(n) = sum from k=1 to 8 of 2^(8-k) * c(16n+2k+1), where c(n) is 1 if n is composite, 0 if n is prime.
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1
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18, 89, 165, 179, 77, 110, 146, 253, 103, 155, 91, 60, 159, 125, 44, 246, 217, 167, 191, 75, 246, 242, 221, 181, 186, 239, 60, 214, 233, 125, 215, 91, 231, 251, 123, 102, 246, 205, 167, 222, 91, 62, 183, 123, 189, 219, 93, 174, 191, 123, 231, 147, 223, 165, 250
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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COMMENTS
| Related to a computer implementation of the sieve of Eratosthenes: Each positive odd number is represented by a bit: 0 if it is prime, 1 if it is composite. The term a(n) contains the 8 bits corresponding to the odd numbers from 16n+3 to 16n+17.
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LINKS
| Cino Hilliard, Program
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EXAMPLE
| In binary, a(0)=00010010, which means that among the odd numbers 3,5,7,9,11,13,15,17, only 9 and 15 are composite.
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MATHEMATICA
| a[n_] := Sum[2^(8-k)*If[PrimeQ[16n+2k+1], 0, 1], {k, 1, 8}]
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CROSSREFS
| Sequence in context: A126405 A141842 A063788 * A059138 A117735 A041624
Adjacent sequences: A066851 A066852 A066853 * A066855 A066856 A066857
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KEYWORD
| nonn
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AUTHOR
| Cino Hilliard (hillcino368(AT)gmail.com), Jan 21 2002
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EXTENSIONS
| Edited by Dean Hickerson (dean.hickerson(AT)yahoo.com), Feb 15 2002
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