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 A036409 #21 Aug 29 2021 16:34:40
%S A036409 0,1,1,1,2,3,4,5,6,8,10,11,14,16,18,21,24,27,30,33,37,41,44,49,53,57,
%T A036409 62,67,72,77,82,88,94,99,106,112,118,125,132,139,146,153,161,169,176,
%U A036409 185,193,201,210,219,228,237,246,256,266,275,286,296
%N A036409 a(n) = ceiling(n^2/11).
%H A036409 Colin Barker, <a href="/A036409/b036409.txt">Table of n, a(n) for n = 0..1000</a>
%H A036409 <a href="/index/Rec#order_13">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1,0,0,0,0,0,0,0,0,1,-2,1).
%F A036409 a(n) = +2 a(n-1) -a(n-2) +a(n-11) -2 a(n-12) +a(n-13). - _R. J. Mathar_, Mar 11 2012
%F A036409 G.f.: x*(1+x)*(1-x+x^2)*(1-x+x^2-x^3+x^4)*(1-x^2+x^4) / ((1-x)^3*(1+x+x^2+x^3+x^4+x^5+x^6+x^7+x^8+x^9+x^10)). - _Colin Barker_, Apr 06 2016
%F A036409 a(m + 11 k) = a(m) + 11 k^2 + 2 m k. - _Robert Israel_, Apr 06 2016
%p A036409 seq(ceil(n^2/11),n=0..100); # _Robert Israel_, Apr 06 2016
%t A036409 Table[Ceiling[n^2/11], {n, 0, 57}] (* _Michael De Vlieger_, Apr 06 2016 *)
%t A036409 LinearRecurrence[{2,-1,0,0,0,0,0,0,0,0,1,-2,1},{0,1,1,1,2,3,4,5,6,8,10,11,14},60] (* _Harvey P. Dale_, Aug 29 2021 *)
%o A036409 (PARI) concat(0, Vec(x*(1+x)*(1-x+x^2)*(1-x+x^2-x^3+x^4)*(1-x^2+x^4) / ((1-x)^3*(1+x+x^2+x^3+x^4+x^5+x^6+x^7+x^8+x^9+x^10)) + O(x^50))) \\ _Colin Barker_, Apr 06 2016
%Y A036409 Cf. A036404, A036405, A036406, A036407, A036408.
%K A036409 nonn,easy
%O A036409 0,5
%A A036409 _N. J. A. Sloane_