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 A135327 #18 Sep 22 2021 03:09:52 %S A135327 1,0,1,3,21,586,50531,16141671 %N A135327 Number of genus-surfaces with n vertices. %H A135327 Gennaro Amendola, <a href="https://arxiv.org/abs/0705.1835">Decomposition and Enumeration of Triangulated Surfaces</a>, Experiment. Math. 17-2 (2008), 153-166; arXiv:0705.1835 [math.CO], 2007, table 2, page 20. %e A135327 a(3) = 1 because the unique surface with 3 vertices is on the closed surface S^2. %e A135327 a(4) = 0 because there are no surface with 4 vertices in Amendola's table. %e A135327 a(5) = 1 because the unique surface with 5 vertices is on the closed surface RP^2. %e A135327 a(6) = 3 because there is a unique surface with 6 vertices on the closed surface T^2 and two on RP^2, so 1 + 2 = 3. %e A135327 a(7) = 21 because there are 5 surfaces with 7 vertices on the closed surface T^2, 6 on RP^2 and 10 on K^2, so 5 + 6 + 10 = 21. %e A135327 a(8) = 46 + 11 + 108 + 284 + 134 + 3 = 586 (see table). %e A135327 a(9) = 230 + 1261 + 59 + 28 + 597 + 6919 + 18166 + 18199 + 4994 + 78 = 50531 (see table). %e A135327 a(10) = 1513 + 50878 + 99177 + 3892 + 356 + 3864 + 82588 + 713714 + 3006044 + 5672821 + 4999850 + 1453490 + 53484 = 16141671. %Y A135327 Cf. A108239. %K A135327 nonn,more %O A135327 3,4 %A A135327 _Jonathan Vos Post_, Dec 06 2007 %E A135327 Edited by _N. J. A. Sloane_, Dec 07 2007 %E A135327 Missing a(5) = 1 inserted by _Andrey Zabolotskiy_, Nov 20 2017 %E A135327 Name corrected by _Andrey Zabolotskiy_, Sep 21 2021