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A124026
Let M = {{0, -1, 2}, {-1, 2, -1}, {2, -1, 0}}; v[1] = {0, 0, 1}; v[n] = M.v[n - 1]; then a(n) = v[n][[1]]
0
0, 2, 1, 14, 26, 132, 364, 1416, 4488, 16016, 53296, 184736, 625184, 2145600, 7303360, 24979584, 85196928, 291057920, 993379072, 3392317952, 11580678656, 39541748736, 134998297600, 460924372992, 1573671536640, 5372896120832
OFFSET
1,2
FORMULA
a(n) = 2*a(n-1)+6*a(n-2)-4*a(n-3). G.f.: -x^2*(3*x-2)/((2*x+1)*(2*x^2-4*x+1)). [Colin Barker, Nov 08 2012]
MATHEMATICA
M = {{0, -1, 2}, {-1, 2, -1}, {2, -1, 0}}; v[1] = {0, 0, 1}; v[n_] := v[n] = M.v[n - 1]; a1 = Table[v[n][[1]], {n, 1, 50}]
LinearRecurrence[{2, 6, -4}, {0, 2, 1}, 40] (* Harvey P. Dale, Jul 18 2015 *)
CROSSREFS
Sequence in context: A276851 A080346 A216445 * A106204 A290603 A083074
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
Edited by N. J. A. Sloane, Nov 04 2006
STATUS
approved