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A062156
Number of n X n matrices over {0,1,2} with all row and column sums equal to 1 or 2.
3
1, 2, 13, 189, 4842, 190080, 10520010, 777018690, 73646397720, 8696221929360, 1249994376199800, 214673857998276600, 43377963701592920400, 10180798532673708139200, 2745082427076790292091600, 842339587833332705318202000, 291745985923439508815578224000
OFFSET
0,2
REFERENCES
I. P. Goulden and D. M. Jackson, Combinatorial Enumeration, Wiley, N.Y., 1983,(Problem 3.4.15).
LINKS
EXAMPLE
There are 13 2 X 2 matrices over {0,1,2} with all row and column sums equal to 1 or 2, cf. A062154.
CROSSREFS
Main diagonal of A062154.
Cf. A062155.
Sequence in context: A193192 A356491 A226865 * A371318 A323209 A239994
KEYWORD
easy,nonn
AUTHOR
Vladeta Jovovic, Jun 06 2001
EXTENSIONS
Terms a(15) and beyond from Andrew Howroyd, Feb 03 2021
STATUS
approved