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Search: id:A109518
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| A109518 |
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a(n)=the (1,2)-entry of the n-th power of the 2 X 2 matrix [0,1;n-1,3(n-1)]. |
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| 1, 3, 38, 783, 22480, 828000, 37231704, 1977187485, 121098539008, 8403438270285, 651608685100000, 55835951178466800, 5239593453691293696, 534383614812622168191, 58857325474654519917440
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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The (1,2)-entry of the n-th power of the 2 X 2 matrix [0,1;1,1] is the Fibonacci number A000045(n).
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EXAMPLE
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a(4)=783 because if M is the 2 X 2 matrix [0,1;3,9], then M^4 is the 2 X 2 matrix [252,783,2349,7299].
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MAPLE
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with(linalg): a:=proc(n) local A, k: A[1]:=matrix(2, 2, [0, 1, n-1, 3*(n-1)]): for k from 2 to n do A[k]:=multiply(A[k-1], A[1]) od: A[n][1, 2] end: seq(a(n), n=1..18);
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MATHEMATICA
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M[n_] = If[n > 1, MatrixPower[{{0, 1}, {n - 1, 3*(n - 1)}}, n], {{0, 1}, {1, 1}}] a = Table[M[n][[1, 2]], {n, 1, 50}]
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CROSSREFS
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Cf. A000045, A000166.
Sequence in context: A005780 A033678 A072331 this_sequence A062155 A099022 A136638
Adjacent sequences: A109515 A109516 A109517 this_sequence A109519 A109520 A109521
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KEYWORD
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nonn
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AUTHOR
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Roger L. Bagula (rlbagulatftn(AT)yahoo.com), Jun 16 2005
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