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 A234278 #22 Jul 09 2025 04:37:50 %S A234278 1,2,5,16,56,333,2147,17456,158022,1604281,17863089,216774585, %T A234278 2844162968,40129498111,605894465441,9748493596584,166520626541070, %U A234278 3009885559478844,57397289146583917,1151666341035710396 %N A234278 The number of circular maps C(n) with n edges regardless of genus. %C A234278 The circular maps are also the maps whose faces could be colored in two colors. %H A234278 M. A. Deryagina and A. D. Mednykh, <a href="http://mi.mathnet.ru/eng/smj2458">On the enumeration of circular maps with given number of edges</a>, Siberian Mathematical Journal, 54, No. 6, 2013, 624-639. %H A234278 M. Deryagina, <a href="ftp://ftp.pdmi.ras.ru/pub/publicat/znsl/v446/p031.pdf">On the enumeration of hypermaps which are self-equivalent with respect to reversing the colors of vertices</a>, Preprint 2016. %F A234278 See formula for C(n) in Theorem 2.1 of Deryagina and Mednykh (2013). %K A234278 nonn %O A234278 1,2 %A A234278 _N. J. A. Sloane_, Dec 28 2013, based on email from Madina Deryagina and Alexander Mednykh