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Search: id:A115952
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| A115952 |
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Expansion of (1-x+x*y)/(1-x^2*y^2)-x^2/(1-x^2*y). |
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+0
4
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| 1, -1, 1, -1, 0, 1, 0, 0, -1, 1, 0, -1, 0, 0, 1, 0, 0, 0, 0, -1, 1, 0, 0, -1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, -1, 1, 0, 0, 0, -1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, -1, 1, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 1, 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, -1, 1, 0, 0, 0, 0, 0, 0, -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 A000007. Diagonal sums are A115953. Inverse is A115954.
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FORMULA
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Number triangle T(n,k)=if(n=k,1,0) OR if(n=2k+2,-1,0) OR if(n=k+1,-(1+(-1)^k)/2,0).
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EXAMPLE
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Triangle begins
1,
-1, 1,
-1, 0, 1,
0, 0, -1, 1,
0, -1, 0, 0, 1,
0, 0, 0, 0, -1, 1,
0, 0, -1, 0, 0, 0, 1,
0, 0, 0, 0, 0, 0, -1, 1,
0, 0, 0, -1, 0, 0, 0, 0, 1,
0, 0, 0, 0, 0, 0, 0, 0, -1, 1,
0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 1,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 1,
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, -1, 1,
0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 1,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 1
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CROSSREFS
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Cf. A115524.
Sequence in context: A128408 A121802 A010056 this_sequence A115524 A117198 A054525
Adjacent sequences: A115949 A115950 A115951 this_sequence A115953 A115954 A115955
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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), Feb 02 2006
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