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Search: id:A128174
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| A128174 |
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Transform, (1,0,1,...) in every column. |
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+0
55
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| 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1
(list; table; graph; listen)
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OFFSET
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1,1
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COMMENT
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Inverse of the triangle = a tridiagonal matrix with (1,1,1...) in the superdiagonal, (0,0,0,...) in the main diagonal and (-1,-1,-1,...) in the subdiagonal.
Riordan array (1/(1-x^2),x) with inverse (1-x^2,x). [From Paul Barry (pbarry(AT)wit.ie), Sep 10 2008]
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FORMULA
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A lower triangular matrix transform, (1, 0, 1,...) in every column; n terms of (1, 0, 1,...) in odd rows; n terms of (0, 1, 0,...) in even rows.
T(n,k)=[k<=n]*(1+(-1)^(n-k))/2; [From Paul Barry (pbarry(AT)wit.ie), Sep 10 2008]
Row sum: sum_{k=1..n} T(n,k) = A004526(n+1). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 29 2009]
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EXAMPLE
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First few rows of the triangle are:
1;
0, 1;
1, 0, 1;
0, 1, 0, 1;
1, 0, 1, 0, 1;
...
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CROSSREFS
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Sequence in context: A129686 A104974 A024711 this_sequence A096055 A125144 A115198
Adjacent sequences: A128171 A128172 A128173 this_sequence A128175 A128176 A128177
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KEYWORD
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nonn,tabl
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AUTHOR
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Gary W. Adamson (qntmpkt(AT)yahoo.com), Feb 17 2007
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