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A075743
For all numbers of the form 6 +- 1 starting with 5,7,11,13,..., '1' indicates prime and '0' indicates composite.
7
1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 0, 1, 1, 1, 1, 0, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 1, 0, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 1, 1, 0, 1, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1, 1, 1, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 1
OFFSET
1,1
COMMENTS
The sequence may described as: for all numbers k(n) [k(n) = 6*ceiling(n/2) + (-1)^n] congruent to -1 or +1 (mod 6) starting with k(n) = {5,7,11,13,...}, a(k(n)) is 1 if k(n) is prime and 0 if k(n) is composite. - Daniel Forgues, Mar 01 2009
LINKS
FORMULA
a(n) = A010051(A007310(n+2)). - Reinhard Zumkeller, Oct 02 2008
a(n) = pi(3n+3) - pi(3n), where pi(n) = A000720(n). - Ridouane Oudra, Sep 02 2019
MATHEMATICA
Boole[PrimeQ/@Flatten[Table[6n+{-1, 1}, {n, 60}]]] (* Harvey P. Dale, Jun 04 2017 *)
CROSSREFS
Absolute value of A156706.
Sequence in context: A167686 A190207 A156706 * A136705 A141646 A129573
KEYWORD
easy,nonn
AUTHOR
Stephan Wagler (stephanwagler(AT)aol.com), Oct 08 2002
EXTENSIONS
Offset corrected by N. J. A. Sloane, Feb 02 2009
STATUS
approved