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 A324217 Number of connected 2n-regular loopless multigraphs on seven unlabeled nodes. 4
 0, 1, 50, 933, 12465, 119906, 864705, 4930446, 23280925, 94308983, 336704397, 1081565510, 3176476119, 8638660038, 21978039571, 52745266132, 120228555981, 261785061087, 547126506745, 1102086250237, 2147107495684 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS There are no (2n+1)-regular graphs satisfying the condition above. Multigraphs are loopless. Initial terms computed with 'nauty and Traces' (see the link). LINKS Table of n, a(n) for n=0..20. Brendan McKay and Adolfo Piperno, nauty and Traces PROG (nauty/shell) for ((n=0; n<30; n=n+2)); do geng -c -d1 7 -q | multig -r\${n} -u; done CROSSREFS Row n=7 of A328682. Cf. A324218. Sequence in context: A329713 A101929 A006360 * A224059 A224045 A224276 Adjacent sequences: A324214 A324215 A324216 * A324218 A324219 A324220 KEYWORD nonn,more,hard AUTHOR Natan Arie Consigli, Apr 30 2019 EXTENSIONS a(10)-a(20) from Andrew Howroyd, Mar 17 2020 STATUS approved

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Last modified September 9 22:43 EDT 2024. Contains 375765 sequences. (Running on oeis4.)