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A138278
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Sequence identical to its third differences in absolute values: a(2n)=3a(2n-1)-3a(2n-2)+2a(2n-3)), a(2n+1)=3a(2n)-3a(2n-1) n > 1.
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0
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1, 2, 4, 8, 16, 24, 40, 80, 120, 200, 400, 600, 1000, 2000, 3000, 5000, 10000, 15000, 25000, 50000, 75000, 125000, 250000, 375000, 625000, 1250000, 1875000, 3125000, 6250000, 9375000, 15625000, 31250000, 46875000, 78125000, 156250000, 234375000, 390625000
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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FORMULA
| a(n) = 5*a(n-3), n>5. G.f.: (3*x^3+6*x^4+4*x^5+1+2*x+4*x^2)/(1-5*x^3). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Mar 23 2010]
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MATHEMATICA
| Join[{1, 2, 4}, LinearRecurrence[{0, 0, 5}, {8, 16, 24}, 40]] (* From Harvey P. Dale, Dec 08 2011 *)
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CROSSREFS
| Cf. A131292, A131665, A132158, A132418, A132658.
Sequence in context: A005943 A008233 A031923 * A089827 A182763 A119311
Adjacent sequences: A138275 A138276 A138277 * A138279 A138280 A138281
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KEYWORD
| nonn,easy
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AUTHOR
| Paul Curtz (bpcrtz(AT)free.fr), May 06 2008
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EXTENSIONS
| Edited by Charles R Greathouse IV (charles.greathouse(AT)case.edu), Mar 18 2010
More terms from Harvey P. Dale, Dec 08 2011
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