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The number of circular maps C(n) with n edges regardless of genus.
1

%I #20 Aug 04 2017 03:59:07

%S 1,2,5,16,56,333,2147,17456,158022,1604281,17863089,216774585,

%T 2844162968,40129498111,605894465441,9748493596584,166520626541070,

%U 3009885559478844,57397289146583917,1151666341035710396

%N The number of circular maps C(n) with n edges regardless of genus.

%C The circular maps are also the maps whose faces could be colored in two colors.

%H 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 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 See formula for C(n) in Theorem 2.1 of Deryagina and Mednykh (2013).

%K nonn

%O 1,2

%A _N. J. A. Sloane_, Dec 28 2013, based on email from Madina Deryagina and Alexander Mednykh.