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 A063733 A variant of Recamán's sequence: a(0)=1, a(n) = a(n-1)-(n-1) if positive and new, else a(n) = a(n-1)+(n-1). 10
 1, 1, 2, 4, 7, 3, 8, 14, 21, 13, 22, 12, 23, 11, 24, 10, 25, 9, 26, 44, 63, 43, 64, 42, 19, 43, 18, 44, 17, 45, 16, 46, 15, 47, 80, 114, 79, 115, 78, 40, 79, 39, 80, 38, 81, 37, 82, 36, 83, 35, 84, 34, 85, 33, 86, 32, 87, 31, 88, 30, 89, 29, 90, 28, 91, 27 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS R. Zumkeller, Table of n, a(n) for n = 0..10000 FORMULA a(n+1) = A005132(n) - 1; A005132 is Recamán's sequence. - Franklin T. Adams-Watters, Mar 12 2010 MATHEMATICA a[0] = 1; a[n_] := a[n] = If[an = a[n-1] - (n-1); an > 0 && FreeQ[Array[a, n-1], an], an, a[n-1] + (n-1)]; Table[a[n], {n, 0, 65}] (* Jean-François Alcover, Feb 18 2018 *) PROG (Haskell) a063733 n = a063733_list !! n a063733_list = 1 : f 0 [1] where    f x ys@(y:_) | u > 0 && u `notElem` ys = u : f (x + 1) (u : ys)                 | otherwise               = v : f (x + 1) (v : ys)                 where u = y - x; v = x + y -- Reinhard Zumkeller, Jul 02 2015 (Python) l=[1] for n in range(1, 101):     x=l[n - 1] - (n - 1)     if x>0 and not x in l: l+=[x, ]     else: l+=[l[n - 1] + (n - 1)] print l # Indranil Ghosh, Jun 02 2017 CROSSREFS See A005132, which is the main entry for this sequence. A063753 = 1 + A005132. A row of A066201. Also a row of A066202. See also A078943. Cf. A141126. Sequence in context: A100707 A302663 A078943 * A187089 A141330 A239324 Adjacent sequences:  A063730 A063731 A063732 * A063734 A063735 A063736 KEYWORD nonn,nice,easy,look AUTHOR N. J. A. Sloane, Sep 05 2001 STATUS approved

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Last modified May 24 23:45 EDT 2020. Contains 334581 sequences. (Running on oeis4.)