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Search: id:A106509
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| A106509 |
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Riordan array ((1+x)/(1+x+x^2),x/(1+x)) read by rows. |
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+0
4
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| 1, 0, 1, -1, -1, 1, 1, 0, -2, 1, 0, 1, 2, -3, 1, -1, -1, -1, 5, -4, 1, 1, 0, 0, -6, 9, -5, 1, 0, 1, 0, 6, -15, 14, -6, 1, -1, -1, 1, -6, 21, -29, 20, -7, 1, 1, 0, -2, 7, -27, 50, -49, 27, -8, 1, 0, 1, 2, -9, 34, -77, 99, -76, 35, -9, 1, -1, -1, -1
(list; table; graph; listen)
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OFFSET
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0,9
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COMMENT
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Row sums are A106510. Diagonal sums are A106511. Inverse of A072405 (when this starts 1,0,1,...).
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FORMULA
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Number triangle T(n, k)=sum{j=0..n-k, (-1)^j*binomial(2n-k-j, j)}
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EXAMPLE
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Triangle begins
1;
0,1;
-1,-1,1;
1,0,-2,1;
0,1,2,-3,1;
-1,-1,-1,5,-4,1;
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CROSSREFS
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Sequence in context: A119339 A037835 A116433 this_sequence A053615 A002819 A037834
Adjacent sequences: A106506 A106507 A106508 this_sequence A106510 A106511 A106512
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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), May 04 2005
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