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 A097875 #5 Dec 31 2023 16:29:15 %S A097875 1,4,24,88,52,2176,41344,55936,22080,2561280,27617280,16570368, %T A097875 34061312,1540980736,23512383488,100462002176,50231001088, %U A097875 3741530783744,4029340844032,5798319751168,4112761683968,526433495547904,12757611732533248,129398633287122944 %N A097875 Denominator of J(n) = A000356(n)/A000309(n) (average number of 4-colorings of rank 0 in a rooted nonseparable map which is trivalent and has 2n nodes). %H A097875 W. T. Tutte, <a href="https://doi.org/10.1137/0117044">On the enumeration of four-colored maps</a>, SIAM J. Appl. Math., 17 (1969), 454-460. %e A097875 1, 5/4, 35/24, 147/88, 99/52, 4719/2176, 102245/41344, ... %Y A097875 Cf. A000356, A000309, A097982. %K A097875 nonn,frac %O A097875 1,2 %A A097875 _N. J. A. Sloane_, Sep 21 2004