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Search: id:A145224
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| A145224 |
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Triangle read by rows: T(n,k) is the number of even permutations (of an n-set) with exactly k fixed points. |
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+0
1
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| 1, 0, 1, 0, 0, 1, 2, 0, 0, 1, 3, 8, 0, 0, 1, 24, 15, 20, 0, 0, 1, 130, 144, 45, 40, 0, 0, 1, 930, 910, 504, 105, 70, 0, 0, 1, 7413, 7440, 3640, 1344, 210, 112, 0, 0, 1, 66752, 66717, 33480, 10920, 3024, 378, 168, 0, 0, 1
(list; table; graph; listen)
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OFFSET
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0,7
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REFERENCES
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Ali, Bashir and Umar, A., "Some combinatorial properties of the alternating group". Southeast Asian Bulletin Math. 32 (2008), 823-830.
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FORMULA
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T(n,k)=C(n,k)A003221(n-k)
Egf.: (x^k(1-x^2/2)e^(-x))/k!(1-x)
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CROSSREFS
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Row sums give A001710, T(n, 0) is A003221, T(n, 1) is A145219, T(n, 2) is A145220
Sequence in context: A045847 A137586 A157608 this_sequence A138157 A073429 A123634
Adjacent sequences: A145221 A145222 A145223 this_sequence A145225 A145226 A145227
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KEYWORD
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nonn,tabl
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AUTHOR
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A. Umar (aumarh(AT)squ.edu.om), Oct 09 2008
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