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A008327
Triangle read by rows: T(n,k) is the number of simple regular bipartite graphs with 2n nodes and degree k, (0 <= k <= n).
9
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 2, 1, 1, 1, 1, 4, 6, 4, 1, 1, 1, 1, 4, 14, 14, 4, 1, 1, 1, 1, 7, 41, 130, 41, 7, 1, 1, 1, 1, 8, 157, 1981, 1981, 157, 8, 1, 1, 1, 1, 12, 725, 62616, 304496, 62616, 725, 12, 1, 1, 1, 1, 14, 4196, 2806508, 78322916
OFFSET
0,13
COMMENTS
This sequence can be derived from A008326 by Euler transform. - Andrew Howroyd, Apr 03 2020
LINKS
B. D. McKay and E. Rogoyski, Latin squares of order ten, Electron. J. Combinatorics, 2 (1995) #N3.
FORMULA
Column k is the Euler transform of column k of A008326. - Andrew Howroyd, Apr 03 2020
EXAMPLE
Triangle begins:
1,
1, 1,
1, 1, 1,
1, 1, 1, 1,
1, 1, 2, 1, 1,
1, 1, 2, 2, 1, 1,
1, 1, 4, 6, 4, 1, 1;
1, 1, 4, 14, 14, 4, 1, 1;
1, 1, 7, 41, 130, 41, 7, 1, 1;
1, 1, 8, 157, 1981, 1981, 157, 8, 1, 1;
...
CROSSREFS
Column k=0..5 are A000012, A000012, A002865, A008325, A333730, A333731.
Row sums are A008324.
Sequence in context: A227690 A063686 A333159 * A133687 A215870 A097587
KEYWORD
nonn,tabl,nice
AUTHOR
EXTENSIONS
More terms from Eric Rogoyski, May 15 1997
Name clarified by Andrew Howroyd, Sep 05 2018
STATUS
approved