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A122431 Riordan array ((1+x)^3,x). 1
1, 3, 1, 3, 3, 1, 1, 3, 3, 1, 0, 1, 3, 3, 1, 0, 0, 1, 3, 3, 1, 0, 0, 0, 1, 3, 3, 1, 0, 0, 0, 0, 1, 3, 3, 1, 0, 0, 0, 0, 0, 1, 3, 3, 1, 0, 0, 0, 0, 0, 0, 1, 3, 3, 1, 0, 0, 0, 0, 0, 0, 0, 1 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Row sums are A115291. Diagonal sums are A113311. Inverse is A122432. Sequence array for C(3,n).

LINKS

Table of n, a(n) for n=0..62.

FORMULA

Number triangle T(n,k)=C(3,n-k)

EXAMPLE

Triangle begins

1,

3,1,

3,3,1,

1,3,3,1,

0,1,3,3,1,

0,0,1,3,3,1,

0,0,0,1,3,3,1,

0,0,0,0,1,3,3,1

CROSSREFS

Sequence in context: A298262 A124814 A122567 * A279340 A089607 A216637

Adjacent sequences:  A122428 A122429 A122430 * A122432 A122433 A122434

KEYWORD

easy,nonn,tabl

AUTHOR

Paul Barry, Sep 04 2006

STATUS

approved

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Last modified July 25 16:39 EDT 2021. Contains 346291 sequences. (Running on oeis4.)