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A151575
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G.f.: (1+x)/(1+x-2*x^2).
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7
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1, 0, 2, -2, 6, -10, 22, -42, 86, -170, 342, -682, 1366, -2730, 5462, -10922, 21846, -43690, 87382, -174762, 349526, -699050, 1398102, -2796202, 5592406, -11184810, 22369622, -44739242, 89478486, -178956970, 357913942, -715827882, 1431655766, -2863311530, 5726623062
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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COMMENTS
| Or, g.f. = (1+x)/((1-x)*(1-2*x)).
A signed version of A078008, which is the main entry.
Contribution from Gary W. Adamson (qntmpkt(AT)yahoo.com), May 25 2009: (Start)
[1, 0, 2, -2, 6, -10, 22, -42, 86,...] = an operator for toothpick sequences. The sequence convolved with A151548 = toothpick sequence A139250. The sequence convolved with A151555 = toothpick sequence A153006. (End)
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FORMULA
| a(n)=(2+(-2)^n)/3 = (-1)^n*A078008(n), n>=0. a(n)=2*A077925(n-2), n>1. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jul 08 2009]
a(n)= A084247(n+1)/2. [From Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Sep 21 2009]
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CROSSREFS
| Sequence in context: A019310 A014113 A078008 * A076907 A153897 A103774
Adjacent sequences: A151572 A151573 A151574 * A151576 A151577 A151578
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KEYWORD
| sign
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), May 25 2009, based on a suggestion from Gary Adamson.
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