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A113310 Riordan array ((1+x)/(1-x),x/(1+x)). 3
1, 2, 1, 2, 1, 1, 2, 1, 0, 1, 2, 1, 1, -1, 1, 2, 1, 0, 2, -2, 1, 2, 1, 1, -2, 4, -3, 1, 2, 1, 0, 3, -6, 7, -4, 1, 2, 1, 1, -3, 9, -13, 11, -5, 1, 2, 1, 0, 4, -12, 22, -24, 16, -6, 1, 2, 1, 1, -4, 16, -34, 46, -40, 22, -7, 1, 2, 1, 0, 5, -20, 50, -80, 86, -62, 29, -8, 1, 2, 1, 1, -5, 25, -70, 130, -166, 148, -91, 37, -9, 1 (list; table; graph; refs; listen; history; internal format)
OFFSET

0,2

COMMENTS

Row sums are A113311. Diagonal sums are A113312. Inverse is A113313. The family of Riordan arrays ((1+x)/(1-(q-1)x),x/(1+x)) allow one to calculate the weight distribution of MDS codes.

REFERENCES

F.J. MacWilliams, N. J. A. Sloane, The Theory of Error-Correcting Codes, North-Holland, 2003, p. 321.

FORMULA

T(n, k)=sum{j=0..n-k, (-1)^j*C(j+k-2, i)}; T(n, k)=sum{j=0..n-k, (-1)^(n-k-j)C(n-j-2, n-j-k); T(n, k)=sum{j=k..n, (-1)^(n-j)*C(n, j)(2^(j-k+1)-1).

EXAMPLE

Triangle begins

1;

2,1;

2,1,1;

2,1,0,1;

2,1,1,-1,1;

2,1,0,2,-2,1;

CROSSREFS

Sequence in context: A174110 A061916 A076348 * A081653 A096860 A128185

Adjacent sequences:  A113307 A113308 A113309 * A113311 A113312 A113313

KEYWORD

easy,sign,tabl

AUTHOR

Paul Barry (pbarry(AT)wit.ie), Oct 25 2005

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Last modified February 15 21:04 EST 2012. Contains 205854 sequences.