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A015572
Expansion of x/(1 - 7*x - 12*x^2).
1
0, 1, 7, 61, 511, 4309, 36295, 305773, 2575951, 21700933, 182817943, 1540136797, 12974772895, 109305051829, 920832637543, 7757489084749, 65352415243759, 550556775723301, 4638126412988215, 39073566199597117, 329172480353038399, 2773090156866434197, 23361700862301500167
OFFSET
0,3
FORMULA
a(n) = 7*a(n-1) + 12*a(n-2).
MATHEMATICA
a[n_]:=(MatrixPower[{{1, 4}, {1, -8}}, n].{{1}, {1}})[[2, 1]]; Table[Abs[a[n]], {n, -1, 40}] (* Vladimir Joseph Stephan Orlovsky, Feb 19 2010 *)
CoefficientList[Series[x/(1-7x-12x^2), {x, 0, 30}], x] (* or *) LinearRecurrence[{7, 12}, {0, 1}, 30] (* Harvey P. Dale, Jan 11 2012 *)
PROG
(Sage) [lucas_number1(n, 7, -12) for n in range(0, 20)] # Zerinvary Lajos, Apr 24 2009
(Magma) [n le 2 select n-1 else 7*Self(n-1) + 12*Self(n-2): n in [1..30]]; // Vincenzo Librandi, Nov 14 2012
(PARI) x='x+O('x^30); concat([0], Vec(x/(1-7*x-12*x^2))) \\ G. C. Greubel, Jan 06 2018
CROSSREFS
Sequence in context: A218228 A155599 A104093 * A066443 A108448 A218473
KEYWORD
nonn,easy
STATUS
approved