cp's OEIS Frontend

A373233 Relative of Hofstadter Q-sequence: a(n) = 0 for n <= 0, a(n) = n for 1 <= n <= 13; a(n) = a(n-a(n-1)) + a(n-a(n-2)) + a(n-a(n-3)) for n > 13.

%I A373233 #10 May 31 2024 15:30:23
%S A373233 1,2,3,4,5,6,7,8,9,10,11,12,13,6,14,15,16,9,17,18,19,12,20,21,22,15,
%T A373233 23,24,17,26,18,26,28,29,22,21,37,32,18,23,38,42,24,26,39,37,37,31,33,
%U A373233 46,32,41,38,40,36,42,49,36,46,38,56,42,48,35,62,31,52,58,59,32,43,53,82
%N A373233 Relative of Hofstadter Q-sequence: a(n) = 0 for n <= 0, a(n) = n for 1 <= n <= 13; a(n) = a(n-a(n-1)) + a(n-a(n-2)) + a(n-a(n-3)) for n > 13.
%C A373233 Similar to A278055 but with different starting values.
%C A373233 a(73) = 82. This is the smallest index for which a(n) > n. So, without the condition that a(n) = 0 for n <= 0, this sequence would be finite and have exactly 73 terms.
%C A373233 Much like the Hofstadter Q-sequence A005185, it is not known if this sequence is defined for all positive n.
%C A373233 a(n) exists for n <= 3*10^7.
%H A373233 Nathan Fox, <a href="/A373233/b373233.txt">Table of n, a(n) for n = 1..10000</a>
%t A373233 a[n_] := a[n] = Which[n < 1, 0, n < 14, n, True, a[n-a[n-1]] + a[n-a[n-2]] + a[n-a[n-3]]]; Array[a, 100] (* _Paolo Xausa_, May 31 2024 *)
%Y A373233 Cf. A005185, A278055, A373227, A373228, A373229, A373230, A373231, A373232.
%Y A373233 Similar sequences based on the Q-recurrence: A278056, A278057, A278058, A278059, A278060, A278061, A278062, A278063, A278064, A278065.
%K A373233 nonn
%O A373233 1,2
%A A373233 _Nathan Fox_, May 28 2024