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

1,2

Comments

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.

Links

Table of n, a(n) for n=1..55.

Formula

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

Example

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.

Crossrefs

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

Sequence in context: A195954 A278532 A352845 * A019176 A143391 A158661

Adjacent sequences: A128086 A128087 A128088 * A128090 A128091 A128092

Keyword

nonn,tabl,frac

Author

Gary W. Adamson, Feb 14 2007

Status

approved