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A285578 a(1) = a(3) = a(4) = 2, a(2) = 1; a(n) = a(a(n-2)) + a(n-a(n-4)-2) for n > 4.

%I A285578 #11 May 01 2017 08:29:43
%S A285578 2,1,2,2,3,3,4,4,4,5,5,6,7,7,8,8,8,8,8,9,9,10,11,12,12,13,13,14,15,15,
%T A285578 16,16,16,16,16,16,16,17,17,18,19,19,20,20,21,21,21,22,22,23,24,25,27,
%U A285578 27,28,28,28,29,29,30,31,31,32,32,32,32,32,32,32,32,32,33,33,34,35
%N A285578 a(1) = a(3) = a(4) = 2, a(2) = 1;  a(n) = a(a(n-2)) + a(n-a(n-4)-2) for n > 4.
%H A285578 Altug Alkan, <a href="/A285578/b285578.txt">Table of n, a(n) for n = 1..10000</a>
%H A285578 Altug Alkan, <a href="/A285578/a285578.png">Plot for first differences</a>
%t A285578 a[1] = a[3] = a[4] = 2; a[2] = 1; a[n_] := a[n] = a[a[n - 2]] + a[n - a[n - 4] - 2]; Array[a, 75] (* _Michael De Vlieger_, Apr 24 2017 *)
%o A285578 (PARI) q=vector(10000); q[1]=q[3]=q[4]=2;q[2]=1; for(n=5, #q, q[n]=q[q[n-2]]+q[n-q[n-4]-2]); vector(10000, n, q[n])
%Y A285578 Cf. A005185, A055748.
%K A285578 nonn
%O A285578 1,1
%A A285578 _Altug Alkan_, Apr 22 2017