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 A183573 #16 Sep 12 2016 16:06:44
%S A183573 2,4,5,7,8,9,10,12,13,14,15,17,18,19,20,21,22,24,25,26,27,28,29,31,32,
%T A183573 33,34,35,36,37,38,40,41,42,43,44,45,46,47,49,50,51,52,53,54,55,56,57,
%U A183573 58,60,61,62,63,64,65,66,67,68,69,71,72,73,74,75,76,77,78,79,80,81,82,84,85,86,87,88,89,90,91,92
%N A183573 a(n) = n + floor(sqrt(2n+1)).
%H A183573 Robert Israel, <a href="/A183573/b183573.txt">Table of n, a(n) for n = 1..10000</a>
%F A183573 From _Robert Israel_, Sep 12 2016: (Start)
%F A183573 a(n+1)=a(n)+2 if n is in A047838, otherwise a(n+1) = a(n)+1.
%F A183573 a(n) = n + A103128(n+1).
%F A183573 G.f.: Theta3(x^2)/(2*(1-x)) + Theta2(x^2)/(2*sqrt(x)*(1-x)) - (1-2*x)*(3-x)/(2*(1-x)^2), where Theta2 and Theta3 are Jacobi Theta functions. (End)
%p A183573 seq(n+floor(sqrt(2*n+1)), n=1..100); # _Robert Israel_, Sep 12 2016
%t A183573 Table[n + Floor@ Sqrt[2 n + 1], {n, 80}] (* _Michael De Vlieger_, Sep 12 2016 *)
%Y A183573 Cf. A047838, A103128, A116940 (complement).
%K A183573 nonn,easy
%O A183573 1,1
%A A183573 _Clark Kimberling_, Jan 05 2011