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A066854 a(n) = Sum_{k=1..8} 2^(8-k) * c(16n+2k+1), where c(j) is 1 if j is composite, 0 if j is prime. 1
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; text; internal format)
OFFSET

0,1

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.

LINKS

Table of n, a(n) for n=0..54.

Cino Hilliard, Program

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.

MATHEMATICA

a[n_] := Sum[2^(8-k)*If[PrimeQ[16n+2k+1], 0, 1], {k, 1, 8}]

CROSSREFS

Sequence in context: A141842 A215191 A063788 * A247901 A059138 A117735

Adjacent sequences:  A066851 A066852 A066853 * A066855 A066856 A066857

KEYWORD

nonn

AUTHOR

Cino Hilliard, Jan 21 2002

EXTENSIONS

Edited by Dean Hickerson, Feb 15 2002

STATUS

approved

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Last modified January 28 06:00 EST 2021. Contains 340490 sequences. (Running on oeis4.)