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A005210 a(n) = |a(n-1) + 2a(n-2) - n|.
(Formerly M0400)
11

%I M0400

%S 1,1,0,2,3,1,0,6,3,5,0,2,11,1,8,6,5,1,8,10,5,3,10,8,3,7,14,0,1,29,0,

%T 26,7,25,4,18,11,9,8,14,11,3,18,20,11,5,20,18,9,5,28,14,17,9,12,26,7,

%U 1,44,14,41,7,26,24,11,7,38,16,23,15,10,32,21,11,22,32,1,13,64,10,57,5,36,38,25,15,22,36

%N a(n) = |a(n-1) + 2a(n-2) - n|.

%C It seems likely that every number will eventually appear.

%D Popular Computing (Calabasas, CA), Z-Sequences, Vol. 4 (No. 42, Sep 1976), pp. 12-16.

%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

%H T. D. Noe and N. J. A. Sloane, <a href="/A005210/b005210.txt">Table of n, a(n) for n = 1..20000</a> [First 1000 terms from T. D. Noe]

%H Popular Computing (Calabasas, CA), <a href="/A005210/a005210.pdf">Z-Sequences, continued.</a> Annotated and scanned copy of pages 14, 15, 16, 18 of Vol. 5 (No. 56, Nov 1977).

%H J. Shallit, <a href="/A001787/a001787.pdf">Letter to N. J. A. Sloane Mar 14, 1979, concerning A001787, A005209, A005210, A005211</a>

%p f:=proc(n) option remember;

%p if n <= 1 then 1 else abs(2*f(n-2)+f(n-1)-n); fi; end;

%p [seq(f(n),n=1..60)]; # _N. J. A. Sloane_, Apr 16 2015

%t RecurrenceTable[{a[1]==a[2]==1,a[n]==Abs[a[n-1]+2a[n-2]-n]},a,{n,90}] (* _Harvey P. Dale_, Mar 23 2012 *)

%o (Haskell)

%o a005210 n = a005210_list !! (n-1)

%o a005210_list = 1 : 1 : (zipWith ((abs .) . (-))

%o [3..] $ zipWith (+) (tail a005210_list) (map (2 *) a005210_list))

%o -- _Reinhard Zumkeller_, Aug 11 2014

%Y Record values and where they occur: A005211 and A242014.

%Y Zeros: A051202. Consecutive equal terms: A256962.

%Y Least inverse: A051203.

%K nonn,easy,nice

%O 1,4

%A _N. J. A. Sloane_

%E More terms from _David W. Wilson_

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Last modified March 21 07:23 EDT 2019. Contains 321367 sequences. (Running on oeis4.)