cp's OEIS Frontend

A373237 Relative of Hofstadter Q-sequence: a(n) = max(0, n+4315) for n <= 0; a(n) = a(n-a(n-1)) + a(n-a(n-2)) + a(n-a(n-3)) for n > 0.

%I A373237 #8 May 30 2024 22:11:36
%S A373237 6,4316,4317,4318,9,4319,4320,4321,12,4322,4323,4324,15,4325,4326,17,
%T A373237 4328,18,4328,4330,4331,22,21,8641,8635,9,18,8650,8653,4324,22,4345,
%U A373237 4350,4328,27,36,4352,8640,4319,39,4353,4359,4323,42,4355,4362,16,4354,4362,4342,40,4354,55,8654,4331,46,4364,4375,25,38,58,17311,8644
%N A373237 Relative of Hofstadter Q-sequence: a(n) = max(0, n+4315) for n <= 0;  a(n) = a(n-a(n-1)) + a(n-a(n-2)) + a(n-a(n-3)) for n > 0.
%C A373237 Sequences like this are more naturally considered with the first nonzero term in position 1. But this sequence would then match A000027 for its first 4315 terms.
%C A373237 This sequence has exactly 4875 terms (of positive index).  a(4875) = 0, so an attempt to calculate a(4876) would refer to itself.
%C A373237 Without the convention that a(n) = 0 for n <= -4315, this sequence would have exactly 24 terms (of positive index), since computing a(25) refers to a(-8616).
%C A373237 If 4315 in this sequence's definition is replaced by any larger number congruent to 3 mod 7, the behavior is essentially the same, though the quasilinear part (see Formula section) lasts longer.
%H A373237 Nathan Fox, <a href="/A373237/b373237.txt">Table of n, a(n) for n = 1..4875</a>
%F A373237 If the index is between 67 and 4313 (inclusive), then a(7n) = 7n+2, a(7n+1) = 7n+4317, a(7n+2) = 7n+4319, a(7n+3) = 7, a(7n+4) = 2n+8675, a(7n+5) = n+8623, a(7n+6) = 4313.
%Y A373237 Cf. A005185, A267501, A278055, A373234, A373235, A373236, A373238, A274058, A373239.
%K A373237 nonn,fini,full
%O A373237 1,1
%A A373237 _Nathan Fox_, May 28 2024