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A162285
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Periodic length 8 sequence [1, -1, -1, 1, -1, 1, 1, -1, ...].
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0
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1, -1, -1, 1, -1, 1, 1, -1, 1, -1, -1, 1, -1, 1, 1, -1, 1, -1, -1, 1, -1, 1, 1, -1, 1, -1, -1, 1, -1, 1, 1, -1, 1, -1, -1, 1, -1, 1, 1, -1, 1, -1, -1, 1, -1, 1, 1, -1, 1, -1, -1, 1, -1, 1, 1, -1, 1, -1, -1, 1, -1, 1, 1, -1, 1, -1, -1, 1, -1, 1, 1, -1, 1, -1, -1, 1, -1, 1, 1, -1, 1, -1, -1, 1, -1, 1, 1, -1, 1, -1, -1, 1, -1, 1, 1, -1, 1, -1, -1, 1, -1, 1, 1, -1, 1
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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FORMULA
| Euler transform of length 8 sequence [ -1, -1, 0, -1, 0, 0, 0, 1].
a(3 - n) = a(n). a(n + 4) = - a(n).
G.f.: (1 - x) * (1 - x^2) / (1 + x^4).
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EXAMPLE
| 1 - x - x^2 + x^3 - x^4 + x^5 + x^6 - x^7 + x^8 - x^9 - x^10 + x^11 + ...
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PROG
| (PARI) {a(n) = (-1)^(n + (n + 2) \ 4)}
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CROSSREFS
| A143431(n+2) = a(n).
Sequence in context: A122188 A000012 A158388 * A071935 A096809 A131561
Adjacent sequences: A162282 A162283 A162284 * A162286 A162287 A162288
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KEYWORD
| sign
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AUTHOR
| Michael Somos, Jun 29 2009
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