OFFSET
1,2
LINKS
Index entries for linear recurrences with constant coefficients, signature (0,4,0,-5,0,2).
FORMULA
From R. J. Mathar, Apr 22 2009: (Start)
a(n) = 4*a(n-2) - 5*a(n-4) + 2*a(n-6).
G.f.: -x*(2*x+1)*(2*x^4 - 2*x^2 + 1)/((2*x^2-1)*(x-1)^2*(1+x)^2).
a(n) = 2*a(n-1) - (n mod 2)*(a(n-1) - (n-3)/2). - Reinhard Zumkeller, Apr 22 2009
MATHEMATICA
Transpose[NestList[Flatten[{Rest[#], 2First[#]-5#[[3]]+ 4#[[5]]}]&, {1, 2, 2, 4, 5, 10}, 40]][[1]] (* Harvey P. Dale, Mar 24 2011 *)
dp[a_, n_]:=Flatten[{{x=a}, Table[{2x, x=2x+m}, {m, 0, n}]}]; A147678=dp[1, 20] (* Zak Seidov, Mar 24 2011 *)
LinearRecurrence[{0, 4, 0, -5, 0, 2}, {1, 2, 2, 4, 5, 10}, 20] (* T. D. Noe, Mar 25 2011 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Apr 21 2009
EXTENSIONS
More terms from R. J. Mathar, Apr 22 2009
STATUS
approved