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 A282081 #10 Sep 30 2019 11:34:33
%S A282081 1,3,9,28,66,126,226,396,651,1001,1491,2184,3108,4284,5796,7752,10197,
%T A282081 13167,16797,21252,26598,32890,40326,49140,59423,71253,84903,100688,
%U A282081 118728,139128,162248,188496,218025,250971,287793,329004,374794,425334,481194,543004
%N A282081 Number of n-element subsets of [n+5] having an even sum.
%H A282081 Alois P. Heinz, <a href="/A282081/b282081.txt">Table of n, a(n) for n = 0..1000</a>
%H A282081 <a href="/index/Rec#order_12">Index entries for linear recurrences with constant coefficients</a>, signature (6,-18,38,-63,84,-92,84,-63,38,-18,6,-1).
%F A282081 G.f.: (x^2-x+1)*(x^4-2*x^3+6*x^2-2*x+1)/((x^2+1)^3*(x-1)^6).
%F A282081 a(n) = A282011(n+5,n).
%F A282081 a(n) = (1+n)*(2+n)*(3+n)*(4+n)*(5+n)/240 + ((-i)^n+i^n)*(8+6*n+n^2)/32 where i=sqrt(-1). - _Colin Barker_, Feb 06 2017
%e A282081 a(0) = 1: {}.
%e A282081 a(1) = 3: {2}, {4}, {6}.
%e A282081 a(2) = 9: {1,3}, {1,5}, {1,7}, {2,4}, {2,6}, {3,5}, {3,7}, {4,6}, {5,7}.
%t A282081 LinearRecurrence[{6,-18,38,-63,84,-92,84,-63,38,-18,6,-1},{1,3,9,28,66,126,226,396,651,1001,1491,2184},40] (* _Harvey P. Dale_, Sep 30 2019 *)
%o A282081 (PARI) Vec((x^2-x+1)*(x^4-2*x^3+6*x^2-2*x+1) / ((x^2+1)^3*(x-1)^6) + O(x^60)) \\ _Colin Barker_, Feb 06 2017
%Y A282081 Cf. A282011.
%K A282081 nonn,easy
%O A282081 0,2
%A A282081 _Alois P. Heinz_, Feb 05 2017