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 A214806 #10 Jan 08 2024 09:40:12 %S A214806 0,0,488,0,11660,375552,0,160680,6652366,146387872,0,1678880,86303920, %T A214806 2298445830,42795288180,0,14771680,918342738,28995928200,629732269188, %U A214806 10663498973088 %N A214806 Triangle read by rows: T(n,k) = number of rooted maps with n vertices and k faces on a non-orientable surface of type 2 (0 <= k <= n). %H A214806 Didier Arquès and Alain Giorgetti, <a href="https://doi.org/10.1016/S0304-3975(98)00230-8">Counting rooted maps on a surface</a>, Theoret. Comput. Sci. 234 (2000), no. 1-2, 255--272. MR1745078 (2001f:05078). %e A214806 Triangle begins: %e A214806 0, %e A214806 0,488, %e A214806 0,11660,375552, %e A214806 0,160680,6652366,146387872, %e A214806 0,1678880,86303920,2298445830,42795288180, %e A214806 0,14771680,918342738,28995928200,629732269188,10663498973088, %e A214806 ... %Y A214806 Diagonals give A118449, A214804, A214805, A214807. Cf. A214337. %K A214806 nonn,tabl %O A214806 0,3 %A A214806 _N. J. A. Sloane_, Jul 28 2012