A128090 Denominators in inverse of A128077, numerators = 1.

1, -4, 4, -18, -18, 9, -48, -48, -48, 16, -100, -100, -100, -100, 25, -180, -180, -180, -180, -180, 36, -294, -294, -294, -294, -294, -294, 49

Offset

1,2

Comments

Row sums of the inverse of A128077: (1/1; -1/4, 1/4; -1/18, -1/18, 1/9; ...) = (1, 0, 0, 0, ...).

Row sums of unsigned terms: (1; 4, 4; 18, 18, 9; ...) = A128091.

A045991 = (0, 0, 4, 18, 48, 100, ...).

Links

Table of n, a(n) for n=1..28.

Formula

Denominators in inverse triangular matrix of A128077, i.e., inverse of (1; 1, 4; 1, 2, 9; 1, 2, 3, 16; ...).

Example

First few rows of the triangle:
     1
    -4,    4;
   -18,  -18,    9;
   -48,  -48,  -48,   16;
  -100, -100, -100, -100, 25;
  ...

Crossrefs

Cf. A128077, A045991, A128091.

Sequence in context: A205110 A116561 A086448 * A119948 A005222 A214166

Adjacent sequences: A128087 A128088 A128089 * A128091 A128092 A128093

Keyword

tabl,frac,sign,more

Author

Gary W. Adamson, Feb 14 2007

Status

approved