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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

Table of n, a(n) for n=1..99.

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.)