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Search: id:A084247
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| A084247 |
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a(n)=-a(n-1)+2a(n-2), a(0)=1,a(1)=2. |
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+0
14
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| 1, 2, 0, 4, -4, 12, -20, 44, -84, 172, -340, 684, -1364, 2732, -5460, 10924, -21844, 43692, -87380, 174764, -349524, 699052, -1398100, 2796204, -5592404, 11184812, -22369620, 44739244, -89478484, 178956972, -357913940, 715827884, -1431655764, 2863311532
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Second differences of Jacobsthal numbers, A001045. - Paul Curtz (bpcrtz(AT)free.fr), Jun 30 2008
Binomial transform of A084246. a(n+1)=A077925(n)+1.
Row sums of triangle in A112555. [From Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Sep 21 2009]
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FORMULA
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a(n)=4/3-(-2)^n/3; G.f.: (1+3x)/((1-x)(1+2x)); E.g.f.: (4exp(x)-exp(-2x))/3.
a(n)= -2*a(n-1)+4 . [From Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Sep 15 2009]
a(n+1)= 2*A151575(n). [From Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Sep 21 2009]
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CROSSREFS
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Cf. A001045.
Sequence in context: A147980 A131772 A021493 this_sequence A070692 A091684 A162397
Adjacent sequences: A084244 A084245 A084246 this_sequence A084248 A084249 A084250
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KEYWORD
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easy,sign
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), May 23 2003
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