This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A283426 #21 May 20 2017 22:00:43 %S A283426 1,1,1,1,2,2,2,4,4,4,4,4,6,8,8,6,8,8,8,8,8,10,14,14,12,12,12,12,14,14, %T A283426 14,16,16,16,16,16,16,16,18,24,24,22,22,16,18,24,26,28,24,22,26,24,24, %U A283426 28,26,26,28,26,28,32,30,30,32,30,32,32,32,32,32,32,32,34,42,42 %N A283426 a(1) = a(2) = a(3) = a(4) = 1; a(n) = a(n-a(n-2)-1) + a(n-a(n-4)-2) for n > 4. %C A283426 For n < 10^5, values of a(n) such that a(n) = a(n + k) for all k = 1..6 are 2^4, 2^5, .., 2^14, 2^15. %H A283426 Altug Alkan, <a href="/A283426/b283426.txt">Table of n, a(n) for n = 1..10000</a> %H A283426 Altug Alkan, <a href="/A283426/a283426.png">Line graph of A283426</a> %t A283426 a[1] = a[2] = a[3] = a[4] = 1; a[n_] := a[n] = a[n - a[n - 2] - 1] + a[n - a[n - 4] - 2]; Array[a, 74] (* _Michael De Vlieger_, May 15 2017 *) %o A283426 (PARI) q=vector(10000); q[1]=q[2]=q[3]=q[4]=1; for(n=5, #q, q[n]=q[n-1-q[n-2]]+q[n-2-q[n-4]]); vector(10000, n, q[n]) %Y A283426 Cf. A005185, A240809. %K A283426 nonn,look %O A283426 1,5 %A A283426 _Altug Alkan_, May 15 2017