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A286331
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Triangle read by rows: T(n,k) is the number of n X n matrices of rank k over F_2.
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5
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1, 1, 1, 1, 9, 6, 1, 49, 294, 168, 1, 225, 7350, 37800, 20160, 1, 961, 144150, 4036200, 19373760, 9999360, 1, 3969, 2542806, 326932200, 8543828160, 39687459840, 20158709760, 1, 16129, 42677334, 23435953128, 2812314375360, 71124337751040, 325139829719040, 163849992929280
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OFFSET
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0,5
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LINKS
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FORMULA
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T(n,k) = Product_{j=0..k-1} (2^n - 2^j)^2/(2^k - 2^j) = A022166(n,k) * Product_{j=0..k-1} (2^n - 2^j).
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EXAMPLE
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Triangle T(n,k) begins:
1;
1, 1;
1, 9, 6;
1, 49, 294, 168;
1, 225, 7350, 37800, 20160;
1, 961, 144150, 4036200, 19373760, 9999360;
...
T(2,1) = 9 because there are 9, 2 X 2 matrices in F_2 that have rank 1: {{0, 0}, {0, 1}}, {{0, 0}, {1, 0}}, {{0, 0}, {1, 1}}, {{0, 1}, {0, 0}}, {{0, 1}, {0, 1}}, {{1, 0}, {0, 0}}, {{1, 0}, {1, 0}}, {{1,1}, {0, 0}}, {{1, 1}, {1, 1}}.
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MAPLE
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T:= (n, k) -> mul((2^n-2^j)^2/(2^k-2^j), j=0..k-1):
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MATHEMATICA
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q = 2; Table[Table[Product[(q^n - q^i)^2/(q^k - q^i), {i, 0, k - 1}], {k, 0, n}], {n, 0, 6}] // Grid
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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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