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Search: id:A005707
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| A005707 |
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a(1) = a(2) = a(3) = a(4) = 1, a(n) = a(a(n-1))+a(n-a(n-1)) for n >= 5.
(Formerly M0251)
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+0
3
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| 1, 1, 1, 1, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 6, 6, 6, 6, 6, 7, 8, 8, 9, 9, 9, 9, 9, 9, 10, 11, 11, 12, 12, 12, 13, 13, 13, 13, 13, 13, 13, 14, 15, 16, 16, 17, 17, 17, 18, 18, 18, 18, 19, 19, 19, 19, 19, 19, 19, 19, 20, 21, 22, 22, 23, 24, 24, 25, 25, 25, 26, 26, 26, 26, 27, 27, 27, 27, 27
(list; graph; listen)
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OFFSET
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1,5
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COMMENT
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It is known that a(n)-a(n-1)=0 or 1 (see the 1991 Monthly reference). - Emeric Deutsch (deutsch(AT)duke.poly.edu), Jun 06 2005
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
Problem E3274, Amer. Math. Monthly, 95 (1988), 555.
Problem E3274, Amer. Math. Monthly, 98, No, 10, (1991), 958-959.
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..1000
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MAPLE
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a[1]:=1: a[2]:=1: a[3]:=1: a[4]:=1: for n from 5 to 100 do a[n]:=a[a[n-1]]+a[n-a[n-1]] od: seq(a[n], n=1..100); (Deutsch)
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CROSSREFS
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Cf. A004001, A005350.
Sequence in context: A087817 A087836 A091497 this_sequence A087828 A110867 A006670
Adjacent sequences: A005704 A005705 A005706 this_sequence A005708 A005709 A005710
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KEYWORD
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nonn,easy,nice
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
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More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Jun 06 2005
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