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A155040 A symmetric (1,-1)-triangle. 1
1, 1, 1, 1, -1, 1, 1, -1, -1, 1, 1, -1, 1, -1, 1, 1, -1, 1, 1, -1, 1, 1, -1, 1, -1, 1, -1, 1, 1, -1, 1, -1, -1, 1, -1, 1, 1, -1, 1, -1, 1, -1, 1, -1, 1, 1, -1, 1, -1, 1, 1, -1, 1, -1, 1, 1, -1, 1, -1, 1, -1, 1, -1, 1, -1, 1, 1, -1, 1, -1, 1, -1, -1, 1, -1, 1, -1, 1, 1, -1, 1, -1, 1, -1, 1, -1, 1 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Row sums are A007877(n+1). Diagonal sums are A155041.

LINKS

Table of n, a(n) for n=0..86.

FORMULA

Number triangle T(n,k)=sum{j=0..n, [j<=k]*[j<=n-k]*(-1)*(((-1)^(j+1)-0^(j+1))-((-1)^j-0^j))}.

EXAMPLE

Triangle begins

.1,

.1, 1,

.1, -1, 1,

.1, -1, -1, 1,

.1, -1, 1, -1, 1,

.1, -1, 1, 1, -1, 1,

.1, -1, 1, -1, 1, -1, 1,

.1, -1, 1, -1, -1, 1, -1, 1,

.1, -1, 1, -1, 1, -1, 1, -1, 1,

.1, -1, 1, -1, 1, 1, -1, 1, -1, 1,

.1, -1, 1, -1, 1, -1, 1, -1, 1, -1, 1,

.1, -1, 1, -1, 1, -1, -1, 1, -1, 1, -1, 1

CROSSREFS

Sequence in context: A098417 A143622 A076479 * A033999 A000012 A162511

Adjacent sequences:  A155037 A155038 A155039 * A155041 A155042 A155043

KEYWORD

easy,sign,tabl

AUTHOR

Paul Barry, Jan 19 2009

STATUS

approved

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Last modified October 18 11:56 EDT 2018. Contains 316321 sequences. (Running on oeis4.)