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A185131
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Irregular triangle C(n,g) counting connected trivalent simple graphs on 2n vertices with girth at least g.
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18
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1, 2, 1, 5, 2, 19, 6, 1, 85, 22, 2, 509, 110, 9, 1, 4060, 792, 49, 1, 41301, 7805, 455, 5, 510489, 97546, 5783, 32, 7319447, 1435720, 90938, 385, 117940535, 23780814, 1620479, 7574, 1, 2094480864, 432757568, 31478584, 181227, 3, 40497138011, 8542471494
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OFFSET
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2,2
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COMMENTS
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The first column is for girth at least 3. The row length is incremented to g-2 when 2n reaches A000066(g).
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LINKS
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EXAMPLE
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1;
2, 1;
5, 2;
19, 6, 1;
85, 22, 2;
509, 110, 9, 1;
4060, 792, 49, 1;
41301, 7805, 455, 5;
510489, 97546, 5783, 32;
7319447, 1435720, 90938, 385;
117940535, 23780814, 1620479, 7574, 1;
2094480864, 432757568, 31478584, 181227, 3;
40497138011, 8542471494, 656783890, 4624501, 21;
845480228069, 181492137812, 14621871204, 122090544, 546, 1;
18941522184590, 4127077143862, 345975648562, 3328929954, 30368, 0;
453090162062723, ?, ?, 93990692595, 1782840, 1;
11523392072541432, ?, ?, 2754222605376, 95079083, 3;
310467244165539782, ?, ?, ?, 4686063120, 13;
8832736318937756165, ?, ?, ?, 220323447962, 155;
?, ?, ?, 10090653722861, 4337;
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CROSSREFS
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Triangular arrays C(n,g) counting connected simple k-regular graphs on n vertices with girth at least g: this sequence (k=3), A184941 (k=4), A184951 (k=5), A184961 (k=6), A184971 (k=7), A184981 (k=8).
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KEYWORD
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nonn,hard,tabf
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AUTHOR
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EXTENSIONS
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Terms C(18,6), C(20,7) and C(21,7) from House of Graphs via Jason Kimberley, May 21 2017
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STATUS
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approved
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