A117352 - OEIS

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A117352

Riordan array (1/(1-2x), x(1-2x)/(1-x)).

1, 2, 1, 4, 1, 1, 8, 1, 0, 1, 16, 1, -1, -1, 1, 32, 1, -2, -2, -2, 1, 64, 1, -3, -2, -2, -3, 1, 128, 1, -4, -1, 0, -1, -4, 1, 256, 1, -5, 1, 3, 3, 1, -5, 1, 512, 1, -6, 4, 6, 6, 6, 4, -6, 1, 1024, 1, -7, 8, 8, 6, 6, 8, 8, -7, 1

(list; table; graph; refs; listen; history; text; internal format)

OFFSET

0,2

COMMENTS

Row sums are A038505. Diagonal sums are A117353. Inverse is A117354.

LINKS

Table of n, a(n) for n=0..65.

FORMULA

Number triangle T(n,k)=sum{j=0..n-k, C(j-k,j)C(n-k,j)}

EXAMPLE

Triangle begins

2, 1,

4, 1, 1,

8, 1, 0, 1,

16, 1, -1, -1, 1,

32, 1, -2, -2, -2, 1,

64, 1, -3, -2, -2, -3, 1

CROSSREFS

Sequence in context: A238415 A283826 A088443 * A137710 A068009 A140168

Adjacent sequences: A117349 A117350 A117351 * A117353 A117354 A117355

KEYWORD

easy,sign,tabl

AUTHOR

Paul Barry, Mar 09 2006

STATUS

approved