cp's OEIS Frontend

A284644 a(1) = a(2) = 2, a(3) = 1; a(n) = a(n-a(n-1)) + a(n-a(n-2)) for n > 3.

%I A284644 #31 Sep 26 2018 22:18:27
%S A284644 2,2,1,3,5,3,5,6,4,6,10,5,7,9,9,10,11,11,12,10,14,11,9,16,14,11,17,21,
%T A284644 11,16,19,17,19,20,19,21,21,22,22,22,24,21,23,23,22,25,25,18,35,26,24,
%U A284644 32,25,22,35,34,20,38,36,27,34,40,20,39,33,36,39,28,40,37,39
%N A284644 a(1) = a(2) = 2, a(3) = 1; a(n) = a(n-a(n-1)) + a(n-a(n-2)) for n > 3.
%C A284644 A "brother" to Hofstadter's Q-sequence (A005185) and A244477 using with different starting values.
%H A284644 Altug Alkan, <a href="/A284644/b284644.txt">Table of n, a(n) for n = 1..10000</a>
%H A284644 Altug Alkan, <a href="/A284644/a284644.png">Alternative scatterplot of A284644</a>
%H A284644 Altug Alkan, <a href="https://doi.org//10.1155/2018/8517125">On a Generalization of Hofstadter's Q-Sequence: A Family of Chaotic Generational Structures</a>, Complexity (2018) Article ID 8517125.
%H A284644 Altug Alkan, Nathan Fox, and Orhan Ozgur Aybar, <a href="https://doi.org/10.1155/2017/2614163">On Hofstadter Heart Sequences</a>, Complexity, 2017, 2614163.
%e A284644 a(4) = 3 because a(4) = a(4 - a(3)) + a(4 - a(2)) = a(3) + a(2) = 3.
%p A284644 A284644:= proc(n) option remember; procname(n-procname(n-1)) +procname(n-procname(n-2)) end proc:
%p A284644 A284644(1):= 2: A284644(2):= 2: A284644(3):= 1:
%p A284644 map(A284644, [$1..1000]);
%t A284644 a[1] = a[2] = 2; a[3] = 1; a[n_] := a[n] = a[n - a[n - 1]] + a[n - a[n - 2]]; Table[a@ n, {n, 72}] (* _Michael De Vlieger_, Apr 02 2017 *)
%o A284644 (PARI) a=vector(1000); a[1]=a[2]=2; a[3]=1; for(n=4, #a, a[n] = a[n-a[n-1]]+a[n-a[n-2]]); a
%Y A284644 Cf. A005185, A244477.
%K A284644 nonn,look
%O A284644 1,1
%A A284644 _Altug Alkan_, Mar 31 2017