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A062156
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Number of n X n matrices over {0,1,2} with all row and column sums equal to 1 or 2.
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2
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1, 2, 13, 189, 4842, 190080, 10520010, 777018690, 73646397720, 8696221929360, 1249994376199800, 214673857998276600, 43377963701592920400, 10180798532673708139200, 2745082427076790292091600
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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REFERENCES
| I. P. Goulden and D. M. Jackson, Combinatorial Enumeration, Wiley, N.Y., 1983,(Problem 3.4.15).
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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.
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CROSSREFS
| Cf. A062154, A062155.
Sequence in context: A137610 A073178 A193192 * A049512 A003507 A003085
Adjacent sequences: A062153 A062154 A062155 * A062157 A062158 A062159
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KEYWORD
| easy,nonn
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AUTHOR
| Vladeta Jovovic (vladeta(AT)eunet.rs), Jun 06 2001
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