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Search: id:A095126
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| A095126 |
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a(n+3) = 2*a(n+2) + 3*a(n+1) - a(n); with a(1) = 4, a(2) = 13, a(3) = 37. |
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5
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| 4, 13, 37, 109, 316, 922, 2683, 7816, 22759, 66283, 193027, 562144, 1637086, 4767577, 13884268, 40434181, 117753589, 342925453, 998677492, 2908377754, 8469862531, 24666180832, 71833571503, 209195822971, 609226179619
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OFFSET
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1,1
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COMMENT
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A sequence generated from a rotated Stirling number of the second kind matrix, companion to A095125.
a(n)/a(n-1) tends to 2.9122291784...an eigenvalue of M and a root of the characteristic polynomial x^3 - 2x^2 - 3x + 1. A095127 is generated from the same polynomial, with the reversal x^3 - 3x^2 - 2x + 1 being the characteristic polynomial of A095128.
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REFERENCES
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R. Aldrovandi, "Special Matrices of Mathematical Physics", World Scientific, 2001, Section 13.3.1, "Inverting Bell Matrices", p. 171.
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FORMULA
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Let M = a rotated Stirling number of the second kind matrix [1 1 1 / 3 1 0 / 1 0 0] (a rotation of [1 0 0 / 1 1 0 / 1 3 1]. Then M^n * [1 1 1] = [A095125(n+1), a(n), A095125(n)].
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EXAMPLE
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a(6) = 922 = 2*316 + 3*109 - 37 = 2*a(5) + 3*a(4) - a(3).
a(5) = 316 since M^5 * [1 1 1] = [202 316 69] = [A095125(6), a(n), A095125(5)]
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MATHEMATICA
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a[n_] := (MatrixPower[{{1, 1, 1}, {3, 1, 0}, {1, 0, 0}}, n].{{1}, {1}, {1}})[[2, 1]]; Table[ a[n], {n, 26}] (from Robert G. Wilson v Jun 01 2004)
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CROSSREFS
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Cf. A095125, A095127, A095128.
Sequence in context: A054761 A080145 A097551 this_sequence A077842 A067633 A091874
Adjacent sequences: A095123 A095124 A095125 this_sequence A095127 A095128 A095129
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KEYWORD
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nonn
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AUTHOR
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Gary W. Adamson (qntmpkt(AT)yahoo.com), May 29 2004
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EXTENSIONS
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Edited, corrected and extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Jun 01 2004
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