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 A118447 #13 Aug 28 2019 09:53:18 %S A118447 4,42,304,1870,10488,55412,280768,1379286,6616360,31144300,144367584, %T A118447 660746892,2991902704,13424189160,59758420736,264191654758, %U A118447 1160934273288,5074150057916,22071747625120,95596117130724 %N A118447 Number of rooted n-edge one-vertex maps on the Klein bottle (dually: one-face maps). %C A118447 One-vertex maps on the projective plane are counted by A000346 and one-vertex maps on a non-orientable genus-3 surface by A118448. Such maps are also called bouquets of loops (and their duals are called unicellular maps). %D A118447 E. R. Canfield, Calculating the number of rooted maps on a surface, Congr. Numerantium, 76 (1990), 21-34. %D A118447 D. M. Jackson and T. I. Visentin, An atlas of the smaller maps in orientable and nonorientable surfaces. CRC Press, Boca Raton, 2001. %F A118447 O.g.f.: (R-1)^2(R+1)(R+3)/8R^5, where R=sqrt(1-4x). %F A118447 Conjecture: -(n-2)*(n-1)^2*a(n) +2*n*(4*n-5)*(n-2)*a(n-1) -8*n*(n-1)*(2*n-3)*a(n-2)=0. - _R. J. Mathar_, Jun 22 2016 %F A118447 a(n) ~ n^(3/2) * 2^(2*n-1) / sqrt(Pi) * (1 - sqrt(Pi/n)/2). - _Vaclav Kotesovec_, Aug 28 2019 %t A118447 ((R - 1)^2 (R + 1) (R + 3)/(8 R^5) /. R -> Sqrt[1 - 4x]) + O[x]^22 // CoefficientList[#, x]& // Drop[#, 2]& (* _Jean-François Alcover_, Aug 28 2019 *) %K A118447 nonn %O A118447 2,1 %A A118447 _Valery A. Liskovets_, May 04 2006