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A116948 Riordan array ((1+2x^2)/(1-x^3),x). 1
1, 0, 1, 2, 0, 1, 1, 2, 0, 1, 0, 1, 2, 0, 1, 2, 0, 1, 2, 0, 1, 1, 2, 0, 1, 2, 0, 1, 0, 1, 2, 0, 1, 2, 0, 1, 2, 0, 1, 2, 0, 1, 2, 0, 1, 1, 2, 0, 1, 2, 0, 1, 2, 0, 1, 0, 1, 2, 0, 1, 2, 0, 1, 2, 0, 1, 2, 0, 1, 2, 0, 1, 2, 0, 1, 2, 0, 1, 1, 2, 0, 1, 2, 0, 1, 2, 0, 1, 2, 0, 1 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,4

COMMENTS

Row sums are A117571. Diagonal sums are A117572. Inverse is A116949.

LINKS

Table of n, a(n) for n=0..90.

FORMULA

Number triangle T(n,k)=2*J(L((n-k+2)/3))[k<=n] where L(j/p) is the Legendre symbol of j and p and J(n)=A001045(n)

EXAMPLE

Triangle begins

1,

0, 1,

2, 0, 1,

1, 2, 0, 1,

0, 1, 2, 0, 1,

2, 0, 1, 2, 0, 1,

1, 2, 0, 1, 2, 0, 1,

0, 1, 2, 0, 1, 2, 0, 1,

2, 0, 1, 2, 0, 1, 2, 0, 1

CROSSREFS

Sequence in context: A077614 A280379 A180793 * A101660 A276771 A062984

Adjacent sequences:  A116945 A116946 A116947 * A116949 A116950 A116951

KEYWORD

easy,nonn,tabl

AUTHOR

Paul Barry, Mar 29 2006

STATUS

approved

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Last modified October 14 09:57 EDT 2019. Contains 327995 sequences. (Running on oeis4.)