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A015545
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Expansion of x/(1-5x-9x^2).
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1
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0, 1, 5, 34, 215, 1381, 8840, 56629, 362705, 2323186, 14880275, 95310049, 610472720, 3910154041, 25045024685, 160416509794, 1027487771135, 6581187443821, 42153327159320, 269997322790989, 1729366558388825
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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LINKS
| Index to sequences with linear recurrences with constant coefficients, signature (5,9).
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FORMULA
| a(n) = 5 a(n-1) + 9 a(n-2).
a(n)=(1/61)*sqrt(61)*{[(5/2)+(1/2)*sqrt(61)]^n-[(5/2)-(1/2)*sqrt(61)]^n}, with n>=0 [From Paolo P. Lava (paoloplava(AT)gmail.com), Jan 13 2009]
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MATHEMATICA
| a[n_]:=(MatrixPower[{{1, 3}, {1, -6}}, n].{{1}, {1}})[[2, 1]]; Table[Abs[a[n]], {n, -1, 40}] [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Feb 19 2010]
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PROG
| (Other) sage: [lucas_number1(n, 5, -9) for n in xrange(0, 21)]# [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Apr 24 2009]
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CROSSREFS
| Sequence in context: A076708 A127816 A024063 * A102436 A033889 A120469
Adjacent sequences: A015542 A015543 A015544 * A015546 A015547 A015548
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KEYWORD
| nonn,easy
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AUTHOR
| Olivier Gerard (olivier.gerard(AT)gmail.com)
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