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A294525
Triangle read by rows: T(n,k) is the number of simple connected graphs on n nodes with k center nodes.
9
1, 0, 1, 1, 0, 1, 2, 2, 0, 2, 8, 4, 4, 0, 5, 29, 19, 18, 18, 0, 28, 180, 84, 119, 118, 129, 0, 223, 1463, 821, 1055, 1426, 1390, 1811, 0, 3151, 20093, 12485, 17297, 24853, 29987, 30515, 46177, 0, 79673, 474063, 343572, 486446, 763319, 1015304, 1247381, 1296986, 2235630, 0, 3853870
OFFSET
1,7
COMMENTS
The column sequences A052437-A052441 also include disconnected graphs. Disconnected graphs have an infinite radius and all nodes are considered a part of the center.
LINKS
Eric Weisstein's World of Mathematics, Graph Center
EXAMPLE
Triangle begins:
: 1;
: 0, 1;
: 1, 0, 1;
: 2, 2, 0, 2;
: 8, 4, 4, 0, 5;
: 29, 19, 18, 18, 0, 28;
: 180, 84, 119, 118, 129, 0, 223;
: 1463, 821, 1055, 1426, 1390, 1811, 0, 3151;
...
CROSSREFS
Columns 1..5 except first term are A052437, A052438, A052439, A052440, A052441.
Row sums give A001349.
Sequence in context: A099064 A280398 A052422 * A011218 A171244 A028305
KEYWORD
nonn,tabl
AUTHOR
Andrew Howroyd, Nov 01 2017
STATUS
approved