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 A052808 #17 Jul 03 2025 03:01:39
%S A052808 0,2,5,24,169,1572,18208,252676,4088138,75571648,1571427096,
%T A052808 36304942704,922615912656,25577663099232,768176940800592,
%U A052808 24845381066244288,860979848497650768,31825036424306681088,1249895536243141292544,51975908060575367916288
%N A052808 E.g.f.: -log(1-x+log(1-x)).
%C A052808 Previous name was: A simple grammar.
%H A052808 INRIA Algorithms Project, <a href="http://ecs.inria.fr/services/structure?nbr=770">Encyclopedia of Combinatorial Structures 770</a>
%F A052808 E.g.f.: -log(1-x+log(1-x)). - _Michael Somos_, Sep 21 2002
%F A052808 a(n) ~ (n-1)! / (1-LambertW(1))^n. - _Vaclav Kotesovec_, Oct 01 2013
%p A052808 spec := [S,{C=Cycle(Z),B=Union(C,Z),S=Cycle(B)},labeled]: seq(combstruct[count](spec,size=n), n=0..20);
%t A052808 With[{nn=30},CoefficientList[Series[-Log[1-x+Log[1-x]],{x,0,nn}],x] Range[ 0,nn]!] (* _Harvey P. Dale_, Mar 27 2013 *)
%o A052808 (PARI) a(n)=if(n<0,0,n!*polcoeff(-log(1-x+log(1-x+x*O(x^n))),n))
%K A052808 easy,nonn
%O A052808 0,2
%A A052808 encyclopedia(AT)pommard.inria.fr, Jan 25 2000
%E A052808 More terms from _Harvey P. Dale_, Mar 27 2013
%E A052808 New name, using e.g.f., by _Vaclav Kotesovec_, Oct 01 2013