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A087844
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a[n] =a[a[a[Min[n-1,Abs[n - a[n-1]]]]]] + a[Abs[n - a[n-3]]].
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1
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1, 1, 1, 2, 3, 4, 4, 4, 4, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 8, 7, 8, 8, 8, 8, 8, 8, 10, 9, 10, 9, 10, 10, 10, 10, 10, 10, 13, 11, 12, 12, 12, 11, 13, 13, 13, 13, 13, 13, 13, 16, 14, 15, 16, 15, 15, 15, 14, 16, 16, 16, 16, 16, 16, 16, 16, 20, 17, 18, 16, 20, 19, 19, 20, 19, 19, 18, 20
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,4
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COMMENTS
| A 4th order recursion based on Hofstadter's Q-sequence A005185, with a built-in skip.
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MATHEMATICA
| Hofstadter3[n_Integer?Positive] := Hofstadter3[n] = Hofstadter3[ Hofstadter3[Hofstadter3[Min[n-1, Abs[n - Hofstadter3[n-1]]]]]] + Hofstadter3[Abs[n - Hofstadter3[n-3]]] Hofstadter3[0]=Hofstadter3[1] = Hofstadter3[2]= Hofstadter3[3]= 1 digits=200 ta=Table[Hofstadter3[n], {n, 1, digits}]
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CROSSREFS
| Cf. A005185, A081831.
Sequence in context: A195850 A174901 A087848 * A189660 A194167 A140427
Adjacent sequences: A087841 A087842 A087843 * A087845 A087846 A087847
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KEYWORD
| nonn
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AUTHOR
| Roger L Bagula (rlbagulatftn(AT)yahoo.com), Oct 07 2003
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EXTENSIONS
| Edited by N. J. A. Sloane (njas(AT)research.att.com), Jun 16 2007
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