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A156174
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Period 5: repeat 1,-1,1,-1,0.
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1
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1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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REFERENCES
| Arthur Gill, Linear Sequential Circuits, McGraw-Hill, 1966, Eq. (17-10).
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LINKS
| Index to sequences with linear recurrences with constant coefficients, signature (-1,-1,-1,-1).
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FORMULA
| G.f.: (1+x^2)/(1+x+x^2+x^3+x^4).
a(n) = -(1/5)*((n mod 5)+((n+1) mod 5)-2*((n+2) mod 5)+2*((n+3) mod 5)-2*((n+4) mod 5)). - Paolo P. Lava, Nov 12 2009
Sum(a(i), i=0..n) = A198517(n). - Bruno Berselli, Nov 02 2011
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PROG
| (PARI) a(n)=[1, -1, 1, -1, 0][n%5+1] \\ Charles R Greathouse IV, Oct 28 2011
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CROSSREFS
| Sequence in context: A120529 A099443 A132342 * A106467 A106468 A030317
Adjacent sequences: A156171 A156172 A156173 * A156175 A156176 A156177
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KEYWORD
| sign,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Nov 06 2009
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