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A135440 a(n) = a(n-1) + 2a(n-2). 6
-1, 4, 2, 10, 14, 34, 62, 130, 254, 514, 1022, 2050, 4094, 8194, 16382, 32770, 65534, 131074, 262142, 524290, 1048574, 2097154, 4194302, 8388610, 16777214, 33554434, 67108862, 134217730, 268435454, 536870914, 1073741822, 2147483650, 4294967294, 8589934594, 17179869182, 34359738370 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
COMMENTS
First differences of A014551. - Reinhard Zumkeller, Jan 02 2013
It can be noticed that, once deprived of its first term, this is an "autosequence" of the second kind, whose companion of the first kind is A014113. - Jean-François Alcover, Aug 19 2022
LINKS
OEIS Wiki, Autosequence
FORMULA
From R. J. Mathar, Feb 19 2008: (Start)
O.g.f.: -1/(2*x-1) - 2/(1+x).
a(n) = 2^n - 2*(-1)^n. (End)
a(n) = 2*A014551(n-1), n>0. - Paul Curtz, Jun 01 2011
E.g.f.: exp(2*x) - 2*exp(-x). - G. C. Greubel, Oct 14 2016
MATHEMATICA
f[n_]:=2/(n+1); x=4; Table[x=f[x]; Numerator[x], {n, 0, 5!}] (* Vladimir Joseph Stephan Orlovsky, Mar 12 2010 *)
LinearRecurrence[{1, 2}, {-1, 4}, 25] (* or *) Table[2^n - 2*(-1)^n, {n, 0, 25}] (* G. C. Greubel, Oct 14 2016 *)
PROG
(Haskell)
a135440 n = a135440_list !! n
a135440_list = zipWith (-) (tail a014551_list) a014551_list
-- Reinhard Zumkeller, Jan 02 2013
CROSSREFS
Sequence in context: A075086 A284782 A128781 * A215500 A188128 A336914
KEYWORD
sign,easy
AUTHOR
Paul Curtz, Feb 18 2008
EXTENSIONS
More terms from R. J. Mathar, Feb 19 2008
STATUS
approved

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Last modified June 23 10:35 EDT 2024. Contains 373643 sequences. (Running on oeis4.)