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A147678 Double, add 0, double, add 1, double, add 2, double, add 3, etc. 4
1, 2, 2, 4, 5, 10, 12, 24, 27, 54, 58, 116, 121, 242, 248, 496, 503, 1006, 1014, 2028, 2037, 4074, 4084, 8168, 8179, 16358, 16370, 32740, 32753, 65506, 65520, 131040, 131055, 262110, 262126, 524252, 524269, 1048538, 1048556, 2097112, 2097131 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
A147675-A147678 are from a quiz that someone asked me to help them with.
LINKS
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)=(1 + (-1)^n)/2 + 2*A016116(n) - A105811(n+3)/4 - 3*(n+1)/4. (End)
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
Sequence in context: A116646 A306318 A091188 * A195865 A222006 A127712
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Apr 21 2009
EXTENSIONS
More terms from R. J. Mathar, Apr 22 2009
STATUS
approved

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Last modified June 2 07:25 EDT 2023. Contains 363081 sequences. (Running on oeis4.)