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A299405 Solution (a(n)) of the system of 5 complementary equations in Comments.

%I A299405 #8 May 01 2018 03:00:18
%S A299405 1,5,9,14,18,22,27,31,35,39,43,48,52,56,60,65,69,73,77,82,86,90,95,99,
%T A299405 103,107,111,116,120,124,128,133,137,141,145,150,154,158,163,167,171,
%U A299405 175,179,184,188,192,196,201,205,209,213,218,222,226,231,235,239
%N A299405 Solution (a(n)) of the system of 5 complementary equations in Comments.
%C A299405 Define sequences a(n), b(n), c(n), d(n) recursively, starting with a(0) = 1, b(0) = 2, c(0) = 3;:
%C A299405 a(n) = least new;
%C A299405 b(n) = least new;
%C A299405 c(n) = least new;
%C A299405 d(n) = least new;
%C A299405 e(n) = a(n) + b(n) + c(n) + d(n);
%C A299405 where "least new k" means the least positive integer not yet placed.
%C A299405 ***
%C A299405 Conjecture: for all n >= 0,
%C A299405 0 <= 17n - 11 - 4 a(n) <= 4
%C A299405 0 <= 17n - 7 - 4 b(n) <= 4
%C A299405 0 <= 17n - 3 - 4 c(n) <= 3
%C A299405 0 <= 17n + 1 - 4 d(n) <= 3
%C A299405 0 <= 17n - 5 - e(n) <= 3
%C A299405 ***
%C A299405 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 A299405 Clark Kimberling, <a href="/A299405/b299405.txt">Table of n, a(n) for n = 0..1000</a>
%e A299405 n:   0  1   2    3   4   5   6   7   8   9
%e A299405 a:   1  5   9   14  18  22  27  31  35  39
%e A299405 b:   2  6   11  15  19  23  28  32  36  40
%e A299405 c:   3  7   12  16  20  24  29  33  37  41
%e A299405 d:   4  8   13  17  21  25  30  34  38  42
%e A299405 e:  10  26  45  62  78  94 114 130 146 162
%t A299405 z = 200;
%t A299405 mex[list_, start_] := (NestWhile[# + 1 &, start, MemberQ[list, #] &]);
%t A299405 a = {1}; b = {2}; c = {3}; d = {4}; e = {}; AppendTo[e,
%t A299405 Last[a] + Last[b] + Last[c] + Last[d]];
%t A299405 Do[{AppendTo[a, mex[Flatten[{a, b, c, d, e}], 1]],
%t A299405    AppendTo[b, mex[Flatten[{a, b, c, d, e}], 1]],
%t A299405    AppendTo[c, mex[Flatten[{a, b, c, d, e}], 1]],
%t A299405    AppendTo[d, mex[Flatten[{a, b, c, d, e}], 1]],
%t A299405    AppendTo[e, Last[a] + Last[b] + Last[c] + Last[d]]}, {z}];
%t A299405 Take[a, 100]  (* A299405 *)
%t A299405 Take[b, 100]  (* A299637 *)
%t A299405 Take[c, 100]  (* A299638 *)
%t A299405 Take[d, 100]  (* A299641 *)
%t A299405 Take[e, 100]  (* A299409 *)
%Y A299405 Cf. A036554, A299634, A299637, A299638,  A299641, A299409.
%K A299405 nonn,easy
%O A299405 0,2
%A A299405 _Clark Kimberling_, Apr 22 2018