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%I #4 Apr 21 2018 20:57:20
%S 2,6,11,18,26,35,45,57,70,84,99,116,135,155,176,198,221,245,270,298,
%T 327,357,388,420,453,487,523,560,598,637,677,718,760,804,850,897,945,
%U 994,1044,1095,1147,1200,1254,1309,1365,1423,1482,1543,1605,1668,1732
%N Solution (b(n)) of the system of 3 equations in Comments.
%C Define sequences a(n), b(n), c(n) recursively, starting with a(0) = 1, b(0) = 2:
%C a(n) = least new;
%C b(n) = a(n) + b(n-1);
%C c(n) = a(n) + 2 b(n);
%C where "least new k" means the least positive integer not yet placed.
%C ***
%C Do these sequences a,b,c partition the positive integers? They differ from the corresponding partitioning sequences A298871, A298872, and A298872. For example, A298872(56) = 2139, whereas A298875(56) = 2138.
%H Clark Kimberling, <a href="/A298875/b298875.txt">Table of n, a(n) for n = 0..1000</a>
%e n: 0 1 2 3 4 5 6 7 8 9
%e a: 1 4 5 7 8 9 10 12 13 14
%e b: 2 6 11 18 26 35 45 57 70 84
%e c: 3 16 27 43 60 30 79 100 126 153
%t z = 200;
%t mex[list_, start_] := (NestWhile[# + 1 &, start, MemberQ[list, #] &]);
%t a = {1}; b = {2}; c = {3};
%t Do[{AppendTo[a, mex[Flatten[{a, b, c}], 1]],
%t AppendTo[b, Last[a] + Last[b]],
%t AppendTo[c, Last[a] + 2 Last[b]]}, {z}];
%t Take[a, 100] (*A298874*)
%t Take[b, 100] (*A298875*)
%t Take[c, 100] (*A298876*)
%Y Cf. A299634, A298871, A298874, A298876.
%K nonn,easy
%O 0,1
%A _Clark Kimberling_, Apr 19 2018