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 A101204 #6 Jul 23 2024 20:34:09 %S A101204 1,0,1,1,0,1,1,1,2,1,3,4,5,4,1,9,16,22,16,7,1,32,75,112,86,41,10,1,133 %N A101204 Triangle read by rows: T(n,k) = number of planar trivalent (or cubic) loopless multigraphs with 2n nodes and exactly k double bonds, for 0 <= k <= n. %C A101204 The entries in the first two rows are "by convention". %D A101204 A. T. Balaban, Enumeration of Cyclic Graphs, pp. 63-105 of A. T. Balaban, ed., Chemical Applications of Graph Theory, Ac. Press, 1976; see p. 92. %e A101204 Triangle begins %e A101204 1, %e A101204 0, 1, %e A101204 1, 0, 1, %e A101204 1, 1, 2, 1, %e A101204 3, 4, 5, 4, 1 %e A101204 9, 16, 22, 16, 7, 1 %e A101204 32, 75, 112, 86, 41, 10, 1 %e A101204 133, ... %Y A101204 Row sums give A005966. First column is A005964 (trivalent connected planar graphs with 2n nodes). Second and third columns give A101205, A101206. %K A101204 nonn,tabl %O A101204 0,9 %A A101204 _N. J. A. Sloane_, Dec 13 2004