cp's OEIS Frontend

A373236 Relative of Hofstadter Q-sequence: a(n) = max(0, n+3201) for n <= 0; a(n) = a(n-a(n-1)) + a(n-a(n-2)) + a(n-a(n-3)) for n > 0.

%I A373236 #8 May 30 2024 22:11:28
%S A373236 6,3202,3203,3204,9,3205,3206,3207,12,3208,3209,3210,15,3211,3212,17,
%T A373236 3214,18,3214,3216,3217,22,21,6413,6407,9,18,6422,6425,3210,22,3231,
%U A373236 3236,3214,27,36,3238,6412,3205,39,3239,3245,3209,42,3241,3248,16,3240,3248,3228,40,3240,55,6426,3217,46,3250,3261,25,38,58,12855,6416,3205
%N A373236 Relative of Hofstadter Q-sequence: a(n) = max(0, n+3201) for n <= 0;  a(n) = a(n-a(n-1)) + a(n-a(n-2)) + a(n-a(n-3)) for n > 0.
%C A373236 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 3201 terms.
%C A373236 This sequence has exactly 3725 terms (of positive index).  a(3725) = 0, so an attempt to calculate a(3726) would refer to itself.
%C A373236 Without the convention that a(n) = 0 for n <= -3201, this sequence would have exactly 24 terms (of positive index), since computing a(25) refers to a(-6388).
%C A373236 If 3201 in this sequence's definition is replaced by any larger number congruent to 2 mod 7, the behavior is essentially the same, though the quasilinear part (see Formula section) lasts longer.
%H A373236 Nathan Fox, <a href="/A373236/b373236.txt">Table of n, a(n) for n = 1..3725</a>
%F A373236 If the index is between 67 and 3199 (inclusive), then a(7n) = 7n+2, a(7n+1) = 7n+3203, a(7n+2) = 7n+3205, a(7n+3) = 7, a(7n+4) = 2n+6447, a(7n+5) = n+6395, a(7n+6) = 3199.
%Y A373236 Cf. A005185, A267501, A278055, A373234, A373235, A373237, A373238, A274058, A373239.
%K A373236 nonn,fini,full
%O A373236 1,1
%A A373236 _Nathan Fox_, May 28 2024