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 A248356 #4 Oct 08 2014 16:55:18
%S A248356 5,8,10,12,14,15,17,18,20,22,23,25,26,27,29,30,32,33,35,36,37,39,40,
%T A248356 41,43,44,45,47,48,49,50,52,53,54,56,57,58,59,61,62,63,64,66,67,68,69,
%U A248356 71,72,73,74,76,77,78,79,80,82,83,84,85,86,88,89,90,91,92
%N A248356 Numbers k such that A248355(k+1) = A248355(k).
%C A248356 The difference sequence of A248355 is (1, 1, 1, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1,...), so that A248356 = (5, 8, 10, 12, 14, 15, ...) and A248357 = (1, 2, 3, 4, 6, 7, 9, 11, 13, 16, 19,...); A248356 and A248357 are a complementary pair.
%H A248356 Clark Kimberling, <a href="/A248356/b248356.txt">Table of n, a(n) for n = 1..9000</a>
%t A248356 z = 200; p[k_] := p[k] = k*Sin[Pi/k]; N[Table[Pi - p[n], {n, 1, z/10}]]
%t A248356 f[n_] := f[n] = Select[Range[z], Pi - p[#] < 1/(2 n) &, 1]
%t A248356 u = Flatten[Table[f[n], {n, 1, z}]] (* A248355 *)
%t A248356 v = Flatten[Position[Differences[u], 0]] (* A248356 *)
%t A248356 w = Flatten[Position[Differences[u], 1]] (* A248357 *)
%t A248356 f = Table[Floor[1/(Pi - p[n])], {n, 1, z}] (* A248358 *)
%Y A248356 Cf. A248355, A248357, A248358, A248347.
%K A248356 nonn,easy
%O A248356 1,1
%A A248356 _Clark Kimberling_, Oct 05 2014