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 A228509 #7 Oct 13 2015 10:11:33
%S A228509 1,2,9,88,1425,32886,992446,37106784,1657248417,86128357150,
%T A228509 5107663394691,340427678198400,25194445531808735,2050156960934135340,
%U A228509 181938723871328671500,17487609556155439051136,1809886850192627028383553,200670984392566362698014110,23730570474434159458296269953
%N A228509 a(n) = binomial(n^2+n+1,n) * (n+1) / (n^2+n+1) for n>=0.
%F A228509 a(n) = (n+1)*A135862(n).
%e A228509 G.f.: A(x) = 1 + 2*x + 9*x^2 + 88*x^3 + 1425*x^4 + 32886*x^5 +...
%t A228509 Table[(Binomial[n^2+n+1,n](n+1))/(n^2+n+1),{n,0,20}] (* _Harvey P. Dale_, Oct 13 2015 *)
%o A228509 (PARI) {a(n)=binomial(n^2+n+1,n)*(n+1)/(n^2+n+1)}
%o A228509 for(n=0,20,print1(a(n),", "))
%Y A228509 Cf. A135862, A135860.
%K A228509 nonn
%O A228509 0,2
%A A228509 _Paul D. Hanna_, Aug 23 2013