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 A204260 Symmetric matrix given by f(i,j)=ceiling(i*j/(i+j)) . 3
 1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 2, 2, 2, 1, 1, 2, 2, 2, 2, 1, 1, 2, 2, 2, 2, 2, 1, 1, 2, 2, 3, 3, 2, 2, 1, 1, 2, 3, 3, 3, 3, 3, 2, 1, 1, 2, 3, 3, 3, 3, 3, 3, 2, 1, 1, 2, 3, 3, 3, 3, 3, 3, 3, 2, 1, 1, 2, 3, 3, 4, 4, 4, 4, 3, 3, 2, 1, 1, 2, 3, 3, 4, 4, 4, 4, 4, 3, 3, 2, 1, 1, 2, 3, 3, 4, 4, 4, 4 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,8 LINKS EXAMPLE Northwest corner: 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 1 2 2 2 2 2 3 3 1 2 2 2 3 3 3 3 1 2 2 3 3 3 3 4 1 2 2 3 3 3 4 4 MATHEMATICA f[i_, j_] := Ceiling[i*j/(i + j)]; m[n_] := Table[f[i, j], {i, 1, n}, {j, 1, n}] TableForm[m[8]] (* 8x8 principal submatrix *) Flatten[Table[f[i, n + 1 - i],   {n, 1, 12}, {i, 1, n}]]  (* A204260 *) Permanent[m_] :=   With[{a = Array[x, Length[m]]},    Coefficient[Times @@ (m.a), Times @@ a]]; Table[Permanent[m[n]], {n, 1, 14}]  (* A204261 *) CROSSREFS Cf. A204261. Sequence in context: A103958 A321696 A321020 * A122923 A113971 A109338 Adjacent sequences:  A204257 A204258 A204259 * A204261 A204262 A204263 KEYWORD nonn,tabl AUTHOR Clark Kimberling, Jan 14 2012 STATUS approved

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Last modified April 23 07:51 EDT 2019. Contains 322381 sequences. (Running on oeis4.)