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A164311
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a(n) = 12*a(n-1) - 33*a(n-2) for n > 1; a(0) = 4, a(1) = 27.
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1
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4, 27, 192, 1413, 10620, 80811, 619272, 4764501, 36738036, 283627899, 2191179600, 16934434533, 130904287596, 1012015111563, 7824339848088, 60495579495477, 467743738958820, 3616570744155099, 27963305544220128, 216212831973523269
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OFFSET
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0,1
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COMMENTS
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LINKS
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FORMULA
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a(n) = ((4+sqrt(3))*(6+sqrt(3))^n + (4-sqrt(3))*(6-sqrt(3))^n)/2.
G.f.: (4-21*x)/(1-12*x+33*x^2).
E.g.f.: (4*cosh(sqrt(3)*x) + sqrt(3)*sinh(sqrt(3)*x))*exp(6*x). - G. C. Greubel, Sep 13 2017
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MATHEMATICA
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LinearRecurrence[{12, -33}, {4, 27}, 50] (* or *) CoefficientList[Series[(4 - 21*x)/(1 - 12*x + 33*x^2), {x, 0, 50}], x] (* G. C. Greubel, Sep 13 2017 *)
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PROG
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(Magma) [ n le 2 select 23*n-19 else 12*Self(n-1)-33*Self(n-2): n in [1..20] ];
(PARI) x='x+O('x^50); Vec((4-21*x)/(1-12*x+33*x^2)) \\ G. C. Greubel, Sep 13 2017
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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