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A127216
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2^n*tetranacci(n) or (2^n)*A001648(n).
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10
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2, 12, 56, 240, 832, 3264, 12672, 48896, 187904, 724992, 2795520, 10776576, 41541632, 160153600, 617414656, 2380201984, 9175957504, 35374497792, 136373075968, 525735034880
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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FORMULA
| a(n) = Trace of matrix [({{2,2,2,2},{2,0,0,0},{0,2,0,0),{0,0,2,0}})^n] a(n) = 2^n Trace of matrix [({{1,1,1,1},{1,0,0,0},{0,1,0,0},{0,0,1,0})^n]
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MATHEMATICA
| Table[Tr[MatrixPower[2*{{1, 1, 1, 1}, {1, 0, 0, 0}, {0, 1, 0, 0}, {0, 0, 1, 0}}, x]], {x, 1, 20}]
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CROSSREFS
| Cf. A087131, A127210, A127211, A127212, A127213, A127214, A127216, A001648.
Sequence in context: A127214 A124723 A122229 * A006659 A194771 A127221
Adjacent sequences: A127213 A127214 A127215 * A127217 A127218 A127219
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KEYWORD
| nonn
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AUTHOR
| Artur Jasinski (grafix(AT)csl.pl), Jan 09 2007
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