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Search: id:A118907
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| A118907 |
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a(0) = 1; a(n) = |a(n-1) - n| if n is has already appeared in the sequence, otherwise a(n) = a(n-1) + n. |
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+0
2
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| 1, 0, 2, 5, 9, 4, 10, 17, 25, 16, 6, 17, 29, 42, 56, 71, 55, 38, 56, 75, 95, 116, 138, 161, 185, 160, 186, 213, 241, 212, 242, 273, 305, 338, 372, 407, 443, 480, 442, 481, 521, 562, 520, 563, 607, 652, 698, 745, 793, 842, 892, 943, 995, 1048, 1102, 1047, 991
(list; graph; listen)
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OFFSET
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0,3
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MAPLE
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a[0]:=1: S:={1}: for n from 1 to 65 do if member(n, S)=true then a[n]:=abs(a[n-1]-n): S:=S union {a[n]} else a[n]:=a[n-1]+n: S:=S union {a[n]} fi od: seq(a[n], n=0..65); - Emeric Deutsch (deutsch(AT)duke.poly.edu), May 07 2006
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MATHEMATICA
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f[s_] := Block[{n, }, n = Length[s]; Return[Append[s, Abs[Last[s] + If[MemberQ[s, n], -n, +n]]]]; ]; Nest[f, {1}, 66] (*Chandler*)
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CROSSREFS
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Cf. A118906, A005132.
Sequence in context: A111761 A021798 A065226 this_sequence A065225 A018878 A021389
Adjacent sequences: A118904 A118905 A118906 this_sequence A118908 A118909 A118910
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KEYWORD
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easy,nonn
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AUTHOR
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Leroy Quet (qq-quet(AT)mindspring.com), May 05 2006
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EXTENSIONS
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Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net) and Emeric Deutsch (deutsch(AT)duke.poly.edu), May 06 2006
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