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A299638 Solution (c(n)) of the system of 5 complementary equations in Comments.

%I A299638 #10 May 01 2018 03:00:31
%S A299638 3,7,12,16,20,24,29,33,37,41,46,50,54,58,63,67,71,75,80,84,88,92,97,
%T A299638 101,105,109,113,118,122,126,131,135,139,143,148,152,156,160,165,169,
%U A299638 173,177,182,186,190,194,199,203,207,211,216,220,224,228,233,237,241
%N A299638 Solution (c(n)) of the system of 5 complementary equations in Comments.
%C A299638 Define sequences a(n), b(n), c(n), d(n) recursively, starting with a(0) = 1, b(0) = 2, c(0) = 3:
%C A299638 a(n) = least new;
%C A299638 b(n) = least new;
%C A299638 c(n) = least new;
%C A299638 d(n) = least new;
%C A299638 e(n) = a(n) + b(n) + c(n) + d(n);
%C A299638 where "least new k" means the least positive integer not yet placed.
%C A299638 ***
%C A299638 Conjecture: for all n >= 0,
%C A299638 0 <= 17n - 11 - 4 a(n) <= 4
%C A299638 0 <= 17n - 7 - 4 b(n) <= 4
%C A299638 0 <= 17n - 3 - 4 c(n) <= 3
%C A299638 0 <= 17n + 1 - 4 d(n) <= 3
%C A299638 0 <= 17n - 5 - e(n) <= 3
%C A299638 ***
%C A299638 The sequences a,b,c,d,e partition the positive integers.  The sequence e can be called the "anti-tetranacci sequence"; see A075326 (anti-Fibonacci numbers) and A265389 (anti-tribonacci numbers).
%H A299638 Clark Kimberling, <a href="/A299638/b299638.txt">Table of n, a(n) for n = 0..1000</a>
%e A299638 n:   0  1   2    3   4   5   6   7   8   9
%e A299638 a:   1  5   9   14  18  22  27  31  35  39
%e A299638 b:   2  6   11  15  19  23  28  32  36  40
%e A299638 c:   3  7   12  16  20  24  29  33  37  41
%e A299638 d:   4  8   13  17  21  25  30  34  38  42
%e A299638 e:  10  26  45  62  78  94 114 130 146 162
%t A299638 z = 200;
%t A299638 mex[list_, start_] := (NestWhile[# + 1 &, start, MemberQ[list, #] &]);
%t A299638 a = {1}; b = {2}; c = {3}; d = {4}; e = {}; AppendTo[e,
%t A299638 Last[a] + Last[b] + Last[c] + Last[d]];
%t A299638 Do[{AppendTo[a, mex[Flatten[{a, b, c, d, e}], 1]],
%t A299638    AppendTo[b, mex[Flatten[{a, b, c, d, e}], 1]],
%t A299638    AppendTo[c, mex[Flatten[{a, b, c, d, e}], 1]],
%t A299638    AppendTo[d, mex[Flatten[{a, b, c, d, e}], 1]],
%t A299638    AppendTo[e, Last[a] + Last[b] + Last[c] + Last[d]]}, {z}];
%t A299638 Take[a, 100]  (* A299405 *)
%t A299638 Take[b, 100]  (* A299637 *)
%t A299638 Take[c, 100]  (* A299638 *)
%t A299638 Take[d, 100]  (* A299641 *)
%t A299638 Take[e, 100]  (* A299409 *)
%Y A299638 Cf. A036554, A299634, A299405, A299637,  A299641, A299409.
%K A299638 nonn,easy
%O A299638 0,1
%A A299638 _Clark Kimberling_, Apr 22 2018