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A344901
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Triangle read by rows: T(n,k) is the number of permutations of length n that have k same elements at the same positions with its inverse permutation for 0 <= k <= n.
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0
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1, 0, 1, 0, 0, 2, 2, 0, 0, 4, 6, 8, 0, 0, 10, 24, 30, 40, 0, 0, 26, 160, 144, 180, 160, 0, 0, 76, 1140, 1120, 1008, 840, 700, 0, 0, 232, 8988, 9120, 8960, 5376, 4200, 2912, 0, 0, 764, 80864, 80892, 82080, 53760, 30240, 19656, 12768, 0, 0, 2620, 809856, 808640, 808920, 547200, 336000, 157248, 95760, 55680, 0, 0, 9496
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OFFSET
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0,6
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LINKS
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FORMULA
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EXAMPLE
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Triangle T(n,k) begins:
1;
0, 1;
0, 0, 2;
2, 0, 0, 4;
6, 8, 0, 0, 10;
24, 30, 40, 0, 0, 26;
160, 144, 180, 160, 0, 0, 76;
1140, 1120, 1008, 840, 700, 0, 0, 232;
8988, 9120, 8960, 5376, 4200, 2912, 0, 0, 764;
...
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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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