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A158678
Period 18: repeat 0,0,0,3,0,0,0,3,0,-3,0,3,0,-3,0,0,0,-3.
0
0, 0, 0, 3, 0, 0, 0, 3, 0, -3, 0, 3, 0, -3, 0, 0, 0, -3, 0, 0, 0, 3, 0, 0, 0, 3, 0, -3, 0, 3, 0, -3, 0, 0, 0, -3, 0, 0, 0, 3, 0, 0, 0, 3, 0, -3, 0, 3, 0, -3, 0, 0, 0, -3
OFFSET
1,4
FORMULA
a(n) = A158674(n) - A158677(n) = a(n-18).
G.f.: 3*(1+x+x^2)*(x^2-x+1)*(x^4-x^2+1)*x^4/((x^6-x^3+1)*(x^6+x^3+1)). - R. J. Mathar, Apr 08 2009
a(n) = - a(n-6) - a(n-12) for n > 12. - Chai Wah Wu, Feb 18 2021
CROSSREFS
Sequence in context: A285014 A219551 A200221 * A117980 A065032 A007514
KEYWORD
sign,easy
AUTHOR
Paul Curtz, Mar 24 2009
EXTENSIONS
Edited by R. J. Mathar, Apr 08 2009
STATUS
approved