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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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3
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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
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OFFSET
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0,7
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LINKS
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FORMULA
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E.g.f.: (x^k(1-x^2/2) e^(-x))/k!(1-x).
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EXAMPLE
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Triangle starts:
1;
0, 1;
0, 0, 1;
2, 0, 0, 1;
3, 8, 0, 0, 1;
24, 15, 20, 0, 0, 1;
...
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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