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A115359 Matrix (1,x)-(x,x^2) in Riordan array notation. 9
1, -1, 1, 0, 0, 1, 0, -1, 0, 1, 0, 0, 0, 0, 1, 0, 0, -1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, -1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, -1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Row sums are 1,0,1,0,1,0... Diagonal sums are A115360. Inverse is A115361.

LINKS

Table of n, a(n) for n=0..119.

FORMULA

Number triangle T(n, k)=if(n=k, 1, 0) OR if(n=2k+1, -1, 0).

EXAMPLE

Triangle begins

1;

-1, 1;

0, 0, 1;

0, -1, 0, 1;

0, 0, 0, 0, 1;

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

0, 0, 0, 0, 0, 0, 1;

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

0, 0, 0, 0, 0, 0, 0, 0, 1;

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

PROG

(PARI) tabl(nn) = {T = matrix(nn, nn, n, k, n--; k--; if ((n==k), 1, if (n==2*k+1, -1, 0))); for (n=1, nn, for (k=1, n, print1(T[n, k], ", "); ); print(); ); } \\ Michel Marcus, Mar 28 2015

CROSSREFS

Sequence in context: A256538 A074910 A115356 * A117906 A090678 A110037

Adjacent sequences:  A115356 A115357 A115358 * A115360 A115361 A115362

KEYWORD

easy,sign,tabl

AUTHOR

Paul Barry, Jan 21 2006

STATUS

approved

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Last modified October 17 08:36 EDT 2019. Contains 328107 sequences. (Running on oeis4.)