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A027446
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Triangle read by rows: square of the lower triangular mean matrix.
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10
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1, 3, 1, 11, 5, 2, 25, 13, 7, 3, 137, 77, 47, 27, 12, 147, 87, 57, 37, 22, 10, 1089, 669, 459, 319, 214, 130, 60, 2283, 1443, 1023, 743, 533, 365, 225, 105, 7129, 4609, 3349, 2509, 1879, 1375, 955, 595, 280, 7381, 4861, 3601, 2761, 2131, 1627, 1207, 847, 532, 252
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OFFSET
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1,2
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COMMENTS
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Numerators of nonzero elements of A^2, written as rows using the least common denominator, where A[i,j] = 1/i if j <= i, 0 if j > i. [Edited by M. F. Hasler, Nov 05 2019]
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LINKS
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FORMULA
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The rational matrix A^2, where the matrix A has elements a[i,j] = 1/A002024(i,j), is equal to A119947(i,j)/A119948(i,j).
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EXAMPLE
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Triangle starts
1
3, 1
11, 5, 2
25, 13, 7, 3
137, 77, 47, 27, 12
147, 87, 57, 37, 22, 10
1089, 669, 459, 319, 214, 130, 60
2283, 1443, 1023, 743, 533, 365, 225, 105
7129, 4609, 3349, 2509, 1879, 1375, 955, 595, 280
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MATHEMATICA
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rows = 10;
M = MatrixPower[Table[If[j <= i, 1/i, 0], {i, 1, rows}, {j, 1, rows}], 2];
T = Table[M[[n]]*LCM @@ Denominator[M[[n]]], {n, 1, rows}];
Table[T[[n, k]], {n, 1, rows}, {k, 1, n}] // Flatten (* Jean-François Alcover, Mar 05 2013, updated May 06 2022 *)
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PROG
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(PARI) A027446_upto(n)={my(M=matrix(n, n, i, j, (j<=i)/i)^2); vector(n, r, M[r, 1..r]*denominator(M[r, 1..r]))} \\ M. F. Hasler, Nov 05 2019
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CROSSREFS
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The row sums give A081528(n), n>=1.
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KEYWORD
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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