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 A006403 M0808 #20 Jan 16 2025 16:24:03 %S A006403 0,1,2,3,6,15,36,114,396,1565,6756,31563,154370,785113,4099948, %T A006403 21870704,118624544,652485364,3631820462,20426666644,115949791342, %U A006403 663640383400,3826858500878,22218232389849,129802836253994 %N A006403 Number of unsensed 2-connected planar maps with n edges. %C A006403 The maps considered here may include parallel edges. - _Andrew Howroyd_, Jan 13 2025 %D A006403 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %D A006403 Timothy R. Walsh, personal communication. %H A006403 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. %H A006403 Timothy R. Walsh, <a href="/A007401/a007401.pdf">Number of sensed planar maps with n edges and m vertices</a>, p. 41. %F A006403 a(n) = (A006402(n) + A006444(n))/2. - _Andrew Howroyd_, Jan 13 2025 %Y A006403 Row sums of A379432. %Y A006403 Cf. A000139 (rooted), A006385, A006402 (sensed), A006407 (without parallel edges), A006444 (achiral). %K A006403 nonn %O A006403 1,3 %A A006403 _N. J. A. Sloane_ %E A006403 a(23)-a(25) added by _Andrew Howroyd_, Jan 13 2025