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Search: id:A155040
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| A155040 |
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A symmetric (1,-1)-triangle. |
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+0
2
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| 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; listen)
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OFFSET
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0,1
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COMMENT
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Row sums are A007877(n+1). Diagonal sums are A155041.
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FORMULA
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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))}.
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EXAMPLE
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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
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CROSSREFS
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Sequence in context: A098417 A143622 A076479 this_sequence A033999 A057077 A162511
Adjacent sequences: A155037 A155038 A155039 this_sequence A155041 A155042 A155043
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KEYWORD
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easy,sign,tabl
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Jan 19 2009
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