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 A128565 #5 May 03 2017 12:38:48
%S A128565 1,2,5,9,29,49,174,285,1068,1717,6655,10569,41926,66013,266338,416687,
%T A128565 1703027,2651355,10947079,16976806,70673825,109256095,457927079,
%U A128565 706071989,2976282415,4579020513,19395654894,29784426945,126688273871,194231327451,829176461458
%N A128565 Column 1 of triangle A128564; a(n) equals the number of permutations of {1..n+2} with [n/2+1] inversions for n>=0.
%F A128565 a(n) = A008302(n+2,[n/2+1]) = coefficient of q^[n/2+1] in the q-factorial of n+2 for n>=0.
%o A128565 (PARI) {a(n)=polcoeff(prod(j=1, n+2, (1-q^j)/(1-q)),(n+2)\2,q)}
%Y A128565 Cf. A008302 (Mahonian numbers); A128564 (triangle), A128566 (column 2).
%K A128565 nonn
%O A128565 0,2
%A A128565 _Paul D. Hanna_, Mar 12 2007