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 A006407 M1157 #26 Jan 17 2025 02:32:49
%S A006407 1,1,2,4,8,20,58,177,630,2410,9772,41423,181586,814412,3722445
%N A006407 Number of unsensed 2-connected simple planar maps with n edges.
%C A006407 A simple planar map is a planar map without loops or parallel edges.
%C A006407 Equivalently, a(n) is the number of embeddings on the sphere of 2-connected planar graphs with n edges. - _Andrew Howroyd_, Mar 27 2021
%D A006407 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H A006407 Timothy R. Walsh, <a href="http://dx.doi.org/10.1137/0604018">Generating nonisomorphic maps without storing them</a>, SIAM J. Algebraic Discrete Methods 4 (1983), no. 2, 161-178.
%F A006407 a(n) = Sum_{k=3..n} A342060(k, n+2-k). - _Andrew Howroyd_, Mar 27 2021
%Y A006407 Cf. A006403, A006405, A006406 (sensed case), A342060, A379437 (rooted).
%K A006407 nonn,more
%O A006407 3,3
%A A006407 _N. J. A. Sloane_
%E A006407 a(11) and a(12) from _Sean A. Irvine_, Apr 03 2017
%E A006407 a(13)-a(17) from _Andrew Howroyd_, Mar 27 2021