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A134668
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Period 6: repeat 1, -1, 0, 0, -1, 1 .
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2
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1, -1, 0, 0, -1, 1, 1, -1, 0, 0, -1, 1, 1, -1, 0, 0, -1, 1, 1, -1, 0, 0, -1, 1, 1, -1, 0, 0, -1, 1, 1, -1, 0, 0, -1, 1, 1, -1, 0, 0, -1, 1, 1, -1, 0, 0, -1, 1, 1, -1, 0, 0, -1, 1, 1, -1, 0, 0, -1, 1, 1, -1, 0, 0, -1, 1, 1, -1, 0, 0, -1, 1, 1, -1, 0, 0, -1, 1, 1, -1, 0, 0, -1, 1, 1, -1, 0, 0, -1, 1, 1, -1, 0, 0, -1, 1, 1, -1, 0, 0, -1, 1, 1, -1, 0
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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COMMENTS
| The Fi2 sums, see A180662, of triangle A108299 equal the terms of this sequence. [Johannes W. Meijer, Aug 11 2011]
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FORMULA
| First differences of A134667.
a(n)=(1/6)*{-2*[(n+1) mod 6]+[(n+2) mod 6]-[(n+4) mod 6]+2*[(n+5) mod 6]}, with n>=0 - Paolo P. Lava (paoloplava(AT)gmail.com), Jan 28 2008
Euler transform of length 6 sequence [ -1, 0, 0, -1, 0, 1]. - Michael Somos Feb 08 2008
a(-1-n) = a(n). - Michael Somos Feb 08 2008
G.f.: (1 - x) * (1 - x^4) / (1 - x^6) = (1 - x) * (1 + x^2) / ((1 - x+ x^2) * (1 + x + x^2)) = (1 - x + x^2 - x^3) / (1 + x^2 + x^4).
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EXAMPLE
| 1 - x - x^4 + x^5 + x^6 - x^7 - x^10 + x^11 + x^12 - x^13 - x^16 + ...
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MAPLE
| A134668 :=proc(n): (1/6)*(-2*((n+1) mod 6)+((n+2) mod 6)-((n+4) mod 6)+2*((n+5) mod 6)) end: seq(A134668(n), n=0..74); # [Johannes W. Meijer, Aug 14 2011]
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PROG
| (PARI) {a(n) = [1, -1, 0, 0, -1, 1][n%6+1]} /* Michael Somos Feb 08 2008 */
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CROSSREFS
| Sequence in context: A068434 A127015 A068432 * A039963 A058840 A154269
Adjacent sequences: A134665 A134666 A134667 * A134669 A134670 A134671
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KEYWORD
| sign,easy
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AUTHOR
| Paul Curtz (bpcrtz(AT)free;fr), Jan 26 2008
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