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a(n) = least k such that s(k) = n, where s = A026370.
3

%I #12 Dec 04 2016 19:46:23

%S 1,2,3,5,6,8,9,11,12,13,14,16,17,19,20,21,22,24,25,27,28,29,30,32,33,

%T 35,36,38,39,41,42,43,44,46,47,49,50,51,52,54,55,57,58,60,61,63,64,65,

%U 66,68,69,71,72,73,74,76,77,79,80,82,83,85,86

%N a(n) = least k such that s(k) = n, where s = A026370.

%C Complement of A026372; also the rank transform (as at A187224) of (A004526 after removal of its first term, leaving 0,1,1,2,2,3,3,4,4,5,5,6,6,...). [From Clark Kimberling, Mar 10 2011]

%t seqA = Table[Floor[n/2], {n, 1, 180}] (* A004526 *)

%t seqB = Table[n, {n, 1, 80}]; (* A000027 *)

%t jointRank[{seqA_, seqB_}] := {Flatten@Position[#1, {_, 1}],

%t Flatten@Position[#1, {_, 2}]} &[Sort@Flatten[{{#1, 1} & /@ seqA,

%t {#1, 2} & /@ seqB}, 1]];

%t limseqU = FixedPoint[jointRank[{seqA, #1[[1]]}] &, jointRank[{seqA, seqB}]][[1]] (* A026371 *)

%t Complement[Range[Length[seqA]], limseqU] (* A026372 *)

%t (* by _Peter J. C. Moses_, Mar 10 2011 *)

%Y Cf. A187422, A026372, A004526.

%K nonn

%O 1,2

%A _Clark Kimberling_