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 A185964 #19 Jul 24 2017 02:04:27
%S A185964 1,-1,0,-2,1,0,4,0,1,-7,-3,-5,10,9,16,-9,-17,-40,-6,19,82,54,10,-135,
%T A185964 -161,-127,153,340,433,0,-527,-1053,-620,434,2013,2200,712,-2880,
%U A185964 -5267,-4491,1981,9635,13350,4897,-12392
%N A185964 Diagonal sums of number triangle A185962.
%H A185964 G. C. Greubel, <a href="/A185964/b185964.txt">Table of n, a(n) for n = 0..1000</a>
%H A185964 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,-2,1).
%F A185964 G.f.: (1-x)^2/(1-x+2*x^3-x^4).
%F A185964 a(n) = Sum_{k=0..floor(n/2)} A185962(n-k,k).
%t A185964 CoefficientList[Series[(1 - x)^2/(1 - x + 2*x^3 - x^4), {x, 0, 50}], x] (* _G. C. Greubel_, Jul 23 2017 *)
%o A185964 (PARI) x='x+O('x^50); Vec((1 - x)^2/(1 - x + 2*x^3 - x^4)) \\ _G. C. Greubel_, Jul 23 2017
%Y A185964 Cf. A185962.
%K A185964 sign,easy
%O A185964 0,4
%A A185964 _Paul Barry_, Feb 07 2011
%E A185964 More terms from _Philippe Deléham_, Feb 07 2012