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A099464
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Trisection of tribonacci numbers.
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4
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0, 1, 7, 44, 274, 1705, 10609, 66012, 410744, 2555757, 15902591, 98950096, 615693474, 3831006429, 23837527729, 148323355432, 922906855808, 5742568741225, 35731770264967, 222332455004452, 1383410902447554, 8607945812375585, 53560898629395777, 333269972246340068
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OFFSET
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0,3
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COMMENTS
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Let A = [1,1,1; 2,4,3; 1,2,2]. a(n) is given by the (1,2) term in A^n.
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LINKS
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Table of n, a(n) for n=0..23.
Index entries for linear recurrences with constant coefficients, signature (7,-5,1).
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FORMULA
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G.f.: x/(1-7*x+5*x^2-x^3).
a(n) = 7a(n-1) -5a(n-2) +a(n-3).
a(n) = A000073(3n).
a(n) = Sum_{i>=n-1} A120987(i,n-1) for n>0. - Alois P. Heinz, Dec 11 2015
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MAPLE
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a:= n-> (<<0|1|0>, <0|0|1>, <1|-5|7>>^n)[3, 1]:
seq(a(n), n=0..30); # Alois P. Heinz, Dec 11 2015
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MATHEMATICA
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LinearRecurrence[{7, -5, 1}, {0, 1, 7}, 30] (* Harvey P. Dale, Jan 14 2016 *)
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CROSSREFS
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Cf. A009943, A120987.
Sequence in context: A218992 A190974 A027279 * A355347 A254660 A093738
Adjacent sequences: A099461 A099462 A099463 * A099465 A099466 A099467
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KEYWORD
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easy,nonn
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AUTHOR
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Paul Barry, Oct 16 2004
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STATUS
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approved
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