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.

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

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 A369419 A059138

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