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 A056474 #13 Aug 22 2017 20:53:12
%S A056474 0,0,0,0,0,0,0,0,1,1,15,15,140,140,1050,1050,6951,6951,42525,42525,
%T A056474 246730,246730,1379400,1379400,7508501,7508501,40075035,40075035,
%U A056474 210766920,210766920,1096190550
%N A056474 Number of palindromic structures using exactly five different symbols.
%C A056474 Permuting the symbols will not change the structure.
%D A056474 M. R. Nester (1999). Mathematical investigations of some plant interaction designs. PhD Thesis. University of Queensland, Brisbane, Australia. [See A056391 for pdf file of Chap. 2]
%H A056474 <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (1,14,-14,-71,71,154,-154,-120,120).
%F A056474 stirling2( [(n+1)/2], 5).
%F A056474 G.f.: -x^9/((x-1)*(2*x-1)*(2*x+1)*(2*x^2-1)*(3*x^2-1)*(5*x^2-1)). [_Colin Barker_, Jul 24 2012]
%t A056474 Table[StirlingS2[Floor[(n+1)/2],5],{n,40}] (* _Harvey P. Dale_, Dec 18 2012 *)
%Y A056474 Cf. A000481, A056470.
%K A056474 nonn,easy
%O A056474 1,11
%A A056474 _Marks R. Nester_