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 A256752 #10 Apr 19 2015 13:08:46
%S A256752 1,3,11,44,190,859,4015,19248,94117,467575,2353443,11975568,61505088,
%T A256752 318406927,1659801852,8704865907,45898065978,243163198928,
%U A256752 1293769867676,6910165762943,37036898772008,199140325574519,1073849938338566
%N A256752 Number of ways to place non-intersecting diagonals in a convex (n+2)-gon so as to create no hexagons.
%H A256752 D. Birmajer, J. B. Gil, and M. Weiner, <a href="http://arxiv.org/abs/1503.05242">Colored partitions of a convex polygon by noncrossing diagonals</a>, arXiv:1503.05242 [math.CO], 2015.
%F A256752 a(n) = (1/(n+1))*Sum_{i=0..floor(n/4)} Sum_{k=i+1..n-3*i} (-1)^i*binomial(n+k,k)*binomial(k,i)*binomial(n-4*i-1,k-i-1), n !== 0 (mod 4),
%F A256752 a(n) = ((-1)^(n/4)/(n+1))*binomial(5*n/4,n/4) + (1/(n+1))*Sum_{i=0..(n/4)-1} Sum_{k=i+1..n-3*i} (-1)^i*binomial(n+k,k)*binomial(k,i)*binomial(n-4*i-1,k-i-1), n == 0 (mod 4).
%e A256752 a(3)=11 because all 11 dissections of the pentagon are allowed, i.e., the null placement, 5 placements of 1 diagonal and 5 placements of two diagonals.
%t A256752 Rest[CoefficientList[(InverseSeries[Series[(y-2*y^2+y^5-y^6)/(1-y), {y, 0, 24}], x]-x)/x, x]]
%Y A256752 Cf. A046736, A054515, A253194.
%K A256752 nonn
%O A256752 1,2
%A A256752 _Michael D. Weiner_, Apr 09 2015