login
Number of twins with n edges.
2

%I #10 Jun 06 2024 11:27:12

%S 0,0,0,11,226,3597,55006,892791,15763270,305360481,6483720916,

%T 150200835113,3774756521566,102339496556342,2977913930684928,

%U 92579209306356230,3062597993515937128,107418845568842941190

%N Number of twins with n edges.

%H Antonio Breda d'Azevedo, Alexander Mednykh, and Roman Nedela, <a href="https://doi.org/10.1016/j.disc.2009.11.017">Enumeration of maps regardless of genus: Geometric approach</a>, Discrete Mathematics, Volume 310, 2010, Pages 1184-1203.

%F a(n) = (A170946(n) - A170947(n)) / 2. [Breda d'Azevedo, Mednykh & Nedela, Corollary 4.8] - _Andrey Zabolotskiy_, Jun 06 2024

%Y Cf. A170946, A170947, A214816.

%K nonn

%O 1,4

%A _N. J. A. Sloane_, Feb 21 2010