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A326898 Number of unlabeled topologies with up to n points. 5
1, 2, 5, 14, 47, 186, 904, 5439, 41418, 404501, 5122188, 84623842, 1828876351, 51701216248, 1908493827243, 91755916071736, 5729050033597431 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
LINKS
EXAMPLE
Non-isomorphic representatives of the a(0) = 1 through a(3) = 14 topologies:
{} {} {} {}
{}{1} {}{1} {}{1}
{}{12} {}{12}
{}{2}{12} {}{123}
{}{1}{2}{12} {}{2}{12}
{}{3}{123}
{}{23}{123}
{}{1}{2}{12}
{}{1}{23}{123}
{}{3}{23}{123}
{}{2}{3}{23}{123}
{}{3}{13}{23}{123}
{}{2}{3}{13}{23}{123}
{}{1}{2}{3}{12}{13}{23}{123}
CROSSREFS
Partial sums of A001930.
The labeled version is A326878.
Sequence in context: A317784 A096402 A007268 * A109156 A143918 A129867
KEYWORD
nonn
AUTHOR
Gus Wiseman, Aug 02 2019
STATUS
approved

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Last modified June 21 13:19 EDT 2024. Contains 373544 sequences. (Running on oeis4.)