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A128090 Denominators in inverse of A128077, numerators = 1. 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 (list; table; graph; refs; listen; history; text; internal format)
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: (1, 8, 45, 160, 425, 936,...). 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 are:

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

AUTHOR

Gary W. Adamson, Feb 14 2007

STATUS

approved

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Last modified August 4 21:32 EDT 2021. Contains 346455 sequences. (Running on oeis4.)