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 A304801 Solution (a(n)) of the complementary equation a(n) = b(n) + b(3n); see Comments. 3

%I

%S 2,8,13,17,22,27,33,38,42,47,53,58,62,68,73,77,82,88,93,97,102,108,

%T 113,117,122,127,133,138,142,147,153,158,162,168,173,177,182,188,193,

%U 198,202,207,213,218,222,227,233,238,242,248,253,257,262,267,273,278

%N Solution (a(n)) of the complementary equation a(n) = b(n) + b(3n); see Comments.

%C Define complementary sequences a(n) and b(n) recursively:

%C b(n) = least new,

%C a(n) = b(n) + b(3n),

%C where "least new" means the least positive integer not yet placed. Empirically, {a(n) - 4*n: n >= 0} = {2,3} and {3*b(n) - 4*n: n >= 0} = {3,4,5,6,7}. See A304799 for a guide to related sequences.

%H Clark Kimberling, <a href="/A304801/b304801.txt">Table of n, a(n) for n = 0..10000</a>

%e b(0) = 1, so that a(0) = 2. Since a(1) = b(1) + b(3), we must have a(1) >= 8, so that b(1) = 3, b(2) = 4, b(3) = 5, b(4) = 6, b(5) = 7, and a(1) = 8.

%t mex[list_, start_] := (NestWhile[# + 1 &, start, MemberQ[list, #] &]);

%t h = 1; k = 3; a = {}; b = {1};

%t AppendTo[a, mex[Flatten[{a, b}], 1]];

%t Do[Do[AppendTo[b, mex[Flatten[{a, b}], Last[b]]], {k}];

%t AppendTo[a, Last[b] + b[[1 + (Length[b] - 1)/k h]]], {500}];

%t Take[a, 200] (* A304801 *)

%t Take[b, 200] (* A304802 *)

%t (* _Peter J. C. Moses_, May 14 2008 *)

%Y Cf. A304799, A304802.

%K nonn,easy

%O 0,1

%A _Clark Kimberling_, May 19 2018

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Last modified June 22 01:32 EDT 2021. Contains 345367 sequences. (Running on oeis4.)