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Search: id:A057427
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| A057427 |
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Sign(n): a(n) = 1 if n>0, = -1 if n<0, = 0 if n = 0. |
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+0
41
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| 0, 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; listen)
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OFFSET
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0,1
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COMMENT
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For nonnegative n, partial sums of A063524 (characteristic function of 1). - Jeremy Gardiner (jeremy.gardiner(AT)btinternet.com), Sep 08 2002
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REFERENCES
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T. M. Macrobert, Functions of a Complex Variable, 4th ed., Macmillan and Co, London, 1958, p. 90
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FORMULA
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G.f.: x/(1-x).
Alternative g.f.: sum(k>=0, t/(1-t^2), t=x^2^k) = 1/(1-x) * sum(k>=0, t-t^2, t=x^2^k) = 1/(1-x)^2 * sum(k>=0, t-2t^2+t^4, t=x^2^k) 2p-1 (from Ralf Stephan)
G.f.: Sum_{k>=0} 2^k x^(2^k)/(1+x^(2^k)). - Michael Somos Sep 11 2005
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PROGRAM
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(PARI) a(n)=sign(n)
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CROSSREFS
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Sequence in context: A011631 A070238 A103131 this_sequence A057428 A062157 A112347
Adjacent sequences: A057424 A057425 A057426 this_sequence A057428 A057429 A057430
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KEYWORD
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easy,nonn,mult
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AUTHOR
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Henry Bottomley (se16(AT)btinternet.com), Sep 05 2000
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