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 A198303 Irregular triangle C(n,g) counting connected trivalent simple graphs on 2n vertices with girth exactly g. 18
 1, 1, 1, 3, 2, 13, 5, 1, 63, 20, 2, 399, 101, 8, 1, 3268, 743, 48, 1, 33496, 7350, 450, 5, 412943, 91763, 5751, 32, 5883727, 1344782, 90553, 385, 94159721, 22160335, 1612905, 7573, 1, 1661723296, 401278984, 31297357, 181224, 3, 31954666517 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,4 COMMENTS The first column is for girth exactly 3. The row length is incremented to g-2 when 2n reaches A000066(g). LINKS F. C. Bussemaker, S. Cobeljic, L. M. Cvetkovic and J. J. Seidel, Computer investigations of cubic graphs, T.H.-Report 76-WSK-01, Technological University Eindhoven, Dept. Mathematics, 1976. EXAMPLE 1; 1, 1; 3, 2; 13, 5, 1; 63, 20, 2; 399, 101, 8, 1; 3268, 743, 48, 1; 33496, 7350, 450, 5; 412943, 91763, 5751, 32; 5883727, 1344782, 90553, 385; 94159721, 22160335, 1612905, 7573, 1; 1661723296, 401278984, 31297357, 181224, 3; 31954666517, 7885687604, 652159389, 4624480, 21; 663988090257, 166870266608, 14499780660, 122089998, 545; 14814445040728, 3781101495300, 342646718608, 3328899586, 30368; CROSSREFS The sum of the n-th row of this sequence is A002851(n). Connected 3-regular simple graphs with girth exactly g: this sequence (triangle); chosen g: A006923 (g=3), A006924 (g=4), A006925 (g=5), A006926 (g=6), A006927 (g=7). Connected 3-regular simple graphs with girth at least g: A185131 (triangle); chosen g: A002851 (g=3), A014371 (g=4), A014372 (g=5), A014374 (g=6), A014375 (g=7), A014376 (g=8). Triangular arrays C(n,g) counting connected simple k-regular graphs on n vertices with girth exactly g: this sequence (k=3), A184940 (k=4), A184950 (k=5), A184960 (k=6), A184970 (k=7), A184980 (k=8). Sequence in context: A218566 A125135 A055456 * A093922 A075555 A075556 Adjacent sequences: A198300 A198301 A198302 * A198304 A198305 A198306 KEYWORD nonn,hard,tabf AUTHOR Jason Kimberley, Nov 16 2011 STATUS approved

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Last modified March 22 17:45 EDT 2023. Contains 361432 sequences. (Running on oeis4.)