This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A246706 #12 Nov 18 2014 03:25:35
%S A246706 2,5,7,9,12,14,16,18,20,23,25,27,29,31,33,35,38,40,42,44,46,48,50,52,
%T A246706 54,57,59,61,63,65,67,69,71,73,75,77,80,82,84,86,88,90,92,94,96,98,
%U A246706 100,102,104,107,109,111,113,115,117,119,121,123,125,127,129,131
%N A246706 Position of last n in A246694 (read as a sequence, with offset changed to 1); complement of A246705.
%C A246706 Note that A246694 has offset 0, so the values here are off by 1 from the positions as given by the indices (b-file or list) in that sequence. - _M. F. Hasler_, Nov 17 2014
%e A246706 A246694 begins with 1, 1, 2, 3, 2, 4, 3, 5, 4, 6, 7, 5, 8, 6, 9, 7, so that, for a(n) = position of first n and b(n) = position of last n, we have a = (1,3,4,6,8,10,...) and b = (2,5,7,9,12,...).
%t A246706 z = 25; t[0, 0] = 1; t[1, 0] = 1; t[1, 1] = 2;
%t A246706 t[n_, 0] := If[OddQ[n], t[n - 1, n - 2] + 1, t[n - 1, n - 1] + 1];
%t A246706 t[n_, 1] := If[OddQ[n], t[n - 1, n - 1] + 1, t[n - 1, n - 2] + 1];
%t A246706 t[n_, k_] := t[n, k - 2] + 1;
%t A246706 u = Flatten[Table[t[n, k], {n, 0, z}, {k, 0, n}]]; (*A246694*)
%t A246706 w[n_] := Flatten[Position[u, n]]; A246706 = Table[Last[w[n]], {n, 1, 3*z}]
%Y A246706 Cf. A246694, A246695, A246705.
%K A246706 nonn,easy
%O A246706 1,1
%A A246706 _Clark Kimberling_, Sep 02 2014