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A120616 Generalized Riordan array (1/sqrt(1+4x^2),(1-sqrt(1+4x^2))/(2x)). 1
1, 0, -1, -2, 0, 1, 0, 3, 0, -1, 6, 0, -4, 0, 1, 0, -10, 0, 5, 0, -1, -20, 0, 15, 0, -6, 0, 1, 0, 35, 0, -21, 0, 7, 0, -1, 70, 0, -56, 0, 28, 0, -8, 0, 1, 0, -126, 0, 84, 0, -36, 0, 9, 0, -1, -252, 0, 210, 0, -120, 0, 45, 0, -10, 0, 1 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,4

COMMENTS

abs(T(n,k)) is A108044. Product by A007318 is A104505.

LINKS

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

FORMULA

Number triangle T(n,k)=C(n,(n+k)/2)(-1)^((n+k)/2)(1+(-1)^(n+k))/2

EXAMPLE

Triangle begins

.1,

.0, -1,

.-2, 0, 1,

.0, 3, 0, -1,

.6, 0, -4, 0, 1,

.0, -10, 0, 5, 0, -1,

.-20, 0, 15, 0, -6, 0, 1,

.0, 35, 0, -21, 0, 7, 0, -1,

.70, 0, -56, 0, 28, 0, -8, 0, 1,

.0, -126, 0, 84, 0, -36, 0, 9, 0, -1,

.-252, 0, 210, 0, -120, 0, 45, 0, -10, 0, 1

CROSSREFS

Sequence in context: A320602 A134511 A112554 * A108044 A104477 A224928

Adjacent sequences:  A120613 A120614 A120615 * A120617 A120618 A120619

KEYWORD

easy,sign,tabl

AUTHOR

Paul Barry, Jun 17 2006

STATUS

approved

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Last modified April 20 06:59 EDT 2021. Contains 343125 sequences. (Running on oeis4.)