Search: id:A066854
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%I A066854
%S A066854 18,89,165,179,77,110,146,253,103,155,91,60,159,125,44,246,217,167,191,
%T A066854 75,246,242,221,181,186,239,60,214,233,125,215,91,231,251,123,102,246,
%U A066854 205,167,222,91,62,183,123,189,219,93,174,191,123,231,147,223,165,250
%N A066854 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.
%C A066854 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.
%H A066854 Cino Hilliard, <a href="a066854.txt">Program</a>
%e A066854 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.
%t A066854 a[n_] := Sum[2^(8-k)*If[PrimeQ[16n+2k+1], 0, 1], {k, 1, 8}]
%Y A066854 Sequence in context: A126405 A141842 A063788 this_sequence A059138 A117735 
               A041624
%Y A066854 Adjacent sequences: A066851 A066852 A066853 this_sequence A066855 A066856 
               A066857
%K A066854 nonn
%O A066854 0,1
%A A066854 Cino Hilliard (hillcino368(AT)gmail.com), Jan 21 2002
%E A066854 Edited by Dean Hickerson (dean.hickerson(AT)yahoo.com), Feb 15 2002

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