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a(n) = a(a(n-3)) + a(n-a(n-3)).
(Formerly M0447)
4

%I M0447 #20 Oct 24 2018 10:54:12

%S 1,1,1,2,3,4,4,4,5,6,6,7,8,8,8,8,9,10,10,11,12,13,13,14,15,16,16,16,

%T 16,16,16,16,17,18,18,19,20,21,21,22,23,24,25,25,26,27,28,29,29,29,29,

%U 29,30,31,32,32,32,32,32,32,32,32,32,32,33,34,34,35,36,37,37,38,39,40,41

%N a(n) = a(a(n-3)) + a(n-a(n-3)).

%D J. Arkin, D. C. Arney, L. S. Dewald and W. E. Ebel, Jr., Families of recursive sequences, J. Rec. Math., 22 (No. 22, 1990), 85-94.

%D B. W. Conolly, ``Meta-Fibonacci sequences,'' in S. Vajda, editor, Fibonacci and Lucas Numbers and the Golden Section. Halstead Press, NY, 1989, pp. 127-138.

%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

%H Iain Fox, <a href="/A006158/b006158.txt">Table of n, a(n) for n = 1..10000</a>

%H I. Vardi, <a href="/A005185/a005185_3.pdf">Email to N. J. A. Sloane, Jun. 1991</a>

%p a := proc(n) option remember: if 1 <= n and n <=3 then RETURN(1) fi: a(a(n-3)) +a(n-a(n-3)) end: for n from 1 to 100 do printf(`%d,`,a(n)) od:

%o (PARI) first(n) = my(res = vector(n, i, 1)); for(x=4, n, res[x]=res[res[x-3]] + res[x-res[x-3]]); res \\ _Iain Fox_, Oct 24 2018

%K nonn

%O 1,4

%A _N. J. A. Sloane_.

%E More terms from _James A. Sellers_, Apr 20 2001