A128078 -id:A128078 - cp's OEIS frontend

A128089 Denominators in inverse of triangle A128078 by rows, n * each term in n-th row of A126615.

1, 4, 4, 6, 18, 9, 8, 24, 48, 16, 10, 30, 60, 100, 25, 12, 36, 72, 120, 180, 36, 14, 42, 84, 140, 210, 294, 49, 16, 48, 96, 160, 240, 336, 448, 64, 18, 54, 108, 180, 270, 378, 504, 648, 81, 20, 60, 120, 200, 300, 420, 560, 720, 900, 100

Offset: 1

Gary W. Adamson, Feb 14 2007

Row sums = A014820: (1, 8, 33, 96, 225, 456, ...).
Denominators of the inverse of A128078: (1/1; 1/4, 1/4; 1/6, 1/18, 1/9; 1/8, 1/24, 1/48, 1/16; ...).
Row sums of this triangle: 1/1, 1/2, 1/3, ...; e.g., (1/8 + 1/24 + 1/48 + 1/16) = 1/4.

			First few rows of the triangle:
   1;
   4,  4;
   6, 18,  9;
   8, 24, 48,  16;
  10, 30, 60, 100,  25;
  12, 36, 72, 120, 180,  36;
  14, 42, 84, 140, 210, 294,  49;
  16, 48, 96, 160, 240, 336, 448,  64;
  ...
Row 4 = (8, 24, 48, 16) = 4 * (2, 6, 12, 4); where (2, 6, 12, 4) = row 4 of A126615.

Cf. A128078, A014820, A006527, A126615, A002260, A128064.

Denominators in inverse triangular matrix of A128078, where A128078 = A002260 * A128064, = (1; -1, 4; -1, -2, 9; -1, -2, -3, 16; ...).

A128077 A128064 * A002260.

Original entry on oeis.org

1, 1, 4, 1, 2, 9, 1, 2, 3, 16, 1, 2, 3, 4, 25, 1, 2, 3, 4, 5, 36, 1, 2, 3, 4, 5, 6, 49, 1, 2, 3, 4, 5, 6, 7, 64

Offset: 1

Gary W. Adamson, Feb 14 2007

Row sums = the pentagonal numbers, A000326: 1, 5, 12, 22, 35, 51, ...

			First few rows of the triangle:
  1;
  1, 4;
  1, 2, 9;
  1, 2, 3, 16;
  1, 2, 3,  4, 25;
  ...

Cf. A128064, A002260, A000326, A128078.

A128064 * A002260 as infinite lower triangular matrices. Triangle read by rows, a(1) = 1; n-th row = first (n-1) terms of (1, 2, 3, ...) followed by n^2.

cp's OEIS Frontend

A128089 Denominators in inverse of triangle A128078 by rows, n * each term in n-th row of A126615.

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