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A061172
Third column of Lucas bisection triangle (odd part).
5
9, 120, 753, 3612, 15040, 57366, 206115, 709152, 2360943, 7659870, 24340184, 76031100, 234116493, 712166952, 2143779645, 6394719216, 18923041360, 55601888562, 162350117703, 471371537040, 1361642740059
OFFSET
0,1
COMMENTS
Numerator of g.f. is row polynomial Sum_{m=0..4} A061187(2,m)*x^m.
FORMULA
a(n) = A060924(n+2, 2).
G.f.: (3-2*x)*(4*x^3-9*x^2+15*x+3)/(1-3*x+x^2)^3.
MATHEMATICA
CoefficientList[Series[(3-2*x)*(4*x^3-9*x^2+15*x+3)/(1-3*x+x^2)^3, {x, 0, 50}], x] (* or *) LinearRecurrence[{9, -30, 45, -30, 9, -1}, {9, 120, 753, 3612, 15040, 57366}, 30] (* G. C. Greubel, Dec 21 2017 *)
PROG
(PARI) x='x+O('x^30); Vec((3-2*x)*(4*x^3-9*x^2+15*x+3)/(1-3*x+x^2)^3) \\ G. C. Greubel, Dec 21 2017
(Magma) I:=[9, 120, 753, 3612, 15040, 57366]; [n le 6 select I[n] else 9*Self(n-1)-30*Self(n-2)+45*Self(n-3)-30*Self(n-4)+9*Self(n-5) - Self(n-6): n in [1..30]]; // G. C. Greubel, Dec 21 2017
CROSSREFS
Sequence in context: A130652 A054051 A159660 * A167593 A214698 A024487
KEYWORD
nonn,easy
AUTHOR
Wolfdieter Lang, Apr 20 2001
STATUS
approved