%I
%S 0,1,4,2,24,26,3,1725,12,14,4,26,123,125,15,5,119,781802,20,22,132896,
%T 6,51,29,31,1220793,23,25,7,429,8869123,532009,532007,532009,532011,
%U 26,8,94,213355,213353,248,33,31,33,1000,9,144,110,112,82,84,210,60,34
%N This is a Recamánlike sequence (cf. A005132). Starting at n, a(n) is the number of steps required to reach zero. On the kth step move a distance of k in the direction of zero. If the number landed on has been landed on before, move a distance of k away from zero instead.
%C The nth triangular number A000217(n) has a(A000217(n)) = n.
%C a(n) + 1 = length of row n in tables A248939 and A248973.  _Reinhard Zumkeller_, Oct 20 2014
%H Jon E. Schoenfield, <a href="/A228474/b228474.txt">Table of n, a(n) for n = 0..10000</a>
%H Gordon Hamilton, <a href="http://www.youtube.com/watch?v=mQdNaofLqVc&feature=youtu.be">Wrecker Ball Sequences</a>, Video, 2013
%H <a href="/index/Rea#Recaman">Index entries for sequences related to Recamán's sequence</a>
%e a(2) = 4 because 2 > 1 > 1 > 4 > 0.
%o (PARI) a(n)={my(M=Map(),k=0); while(n, k++; mapput(M,n,1); my(t=if(n>0, k, +k)); n+=if(mapisdefined(M,n+t),t,t)); k} \\ _Charles R Greathouse IV_, Aug 18 2014, revised _Andrew Howroyd_, Feb 28 2018
%o (Haskell)
%o a228474 = subtract 1 . length . a248939_row  _Reinhard Zumkeller_, Oct 20 2014
%Y Cf. A000217, A005132.
%Y Cf. A248939, A248973.
%K walk,nonn
%O 0,3
%A _Gordon Hamilton_, Aug 23 2013
%E More terms from _Jon E. Schoenfield_, Jan 10 2014
