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A107856
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a(n) = 2*a(n-2)+4*a(n-4)+a(n-6), n>9.
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0
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1, 1, 1, 0, 4, 4, 11, 7, 37, 30, 122, 92, 403, 311, 1331, 1020, 4396, 3376, 14519, 11143, 47953, 36810, 158378, 121568, 523087, 401519, 1727639, 1326120, 5706004, 4379884, 18845651, 14465767, 62242957, 47777190, 205574522, 157797332
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,5
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FORMULA
| Limit_{n->infinity} a(n)/a(n-1) alternates between 0.767592... and 4.3027...
G.f.: x*(1+x+x^2)*(2*x^6+2*x^2-1)/( (1+x^2)*(x^4+3*x^2-1)) [Sep 28 2009]
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MATHEMATICA
| M[n_] := If [Mod[n, 2] == 0, {{0, 1, 0, 0}, {0, 0, 1, 0}, {0, 0, 0, 1}, {1, 3, 0, -3}}, {{0, 1, 0, 0}, {0, 0, 1, 0}, {0, 0, 0, 1}, {0, 0, 1, 1}}] v[1] = {1, 1, 1, 0} v[n_] := v[n] = M[n].v[n - 1] a0 = Table[Abs[v[n][[1]]], {n, 1, 50}]
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CROSSREFS
| Sequence in context: A117881 A161433 A180498 * A168373 A128499 A048223
Adjacent sequences: A107853 A107854 A107855 * A107857 A107858 A107859
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KEYWORD
| nonn,easy
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AUTHOR
| Roger L. Bagula (rlbagulatftn(AT)yahoo.com), Jun 12 2005
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EXTENSIONS
| Definition replaced by recurrence by the Associate Editors of the OEIS, Sep 28 2009
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