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 A011869 #25 Jul 08 2025 02:41:24
%S A011869 0,0,0,0,0,1,1,2,3,4,5,6,8,9,11,13,15,17,19,21,23,26,28,31,34,37,40,
%T A011869 43,47,50,54,58,62,66,70,74,78,83,87,92,97,102,107,112,118,123,129,
%U A011869 135,141,147,153,159,165,172,178,185,192,199,206,213,221,228,236,244,252,260
%N A011869 a(n) = floor(n*(n-1)/16).
%H A011869 Matthew House, <a href="/A011869/b011869.txt">Table of n, a(n) for n = 0..10000</a>
%H A011869 <a href="/index/Rec#order_17">Index entries for linear recurrences with constant coefficients</a>, signature (3,-4,4,-4,4,-4,4,-4,4,-4,4,-4,4,-4,4,-3,1).
%F A011869 G.f.: -((x^5 (1-x+x^2) (1-x+x^2-x^3+x^4-x^5+x^6))/((-1+x)^3 (1+x^2) (1+x^4) (1+x^8)))
%t A011869 Table[Floor[(n(n-1))/16],{n,0,70}] (* or *) LinearRecurrence[{3,-4,4,-4,4,-4,4,-4,4,-4,4,-4,4,-4,4,-3,1},{0,0,0,0,0,1,1,2,3,4,5,6,8,9,11,13,15},70] (* _Harvey P. Dale_, May 23 2019 *)
%o A011869 (Magma) [(n*(n-1) div 16) : n in [0..70]]; // _Vincenzo Librandi_, May 26 2019
%Y A011869 Cf. A011861.
%K A011869 nonn
%O A011869 0,8
%A A011869 _N. J. A. Sloane_