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 A183868 #14 Jan 21 2019 20:05:42
%S A183868 3,5,7,8,9,11,12,14,15,16,17,19,20,21,23,24,25,26,27,29,30,31,32,34,
%T A183868 35,36,37,38,39,41,42,43,44,45,47,48,49,50,51,52,53,55,56,57,58,59,60,
%U A183868 62,63,64,65,66,67,68,69,71,72,73,74
%N A183868 a(n) = n + floor(2*sqrt(n+1)); complement of A079524.
%p A183868 A183868 := proc(n) n+floor(2*sqrt(n+1)) ; end proc: # _R. J. Mathar_, Feb 06 2011
%t A183868 Table[n+Floor[2*Sqrt[n+1]],{n,60}] (* _Harvey P. Dale_, Nov 05 2013 *)
%Y A183868 Cf. A079524.
%K A183868 nonn,easy
%O A183868 1,1
%A A183868 _Clark Kimberling_, Jan 07 2011