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Search: id:A113680
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| A113680 |
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Riordan array ((1-x-2x^2)/(1-x),x). |
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+0
3
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| 1, 0, 1, -2, 0, 1, -2, -2, 0, 1, -2, -2, -2, 0, 1, -2, -2, -2, -2, 0, 1, -2, -2, -2, -2, -2, 0, 1, -2, -2, -2, -2, -2, -2, 0, 1, -2, -2, -2, -2, -2, -2, -2, 0, 1, -2, -2, -2, -2, -2, -2, -2, -2, 0, 1, -2, -2, -2, -2, -2, -2, -2, -2, -2, 0, 1, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, 0, 1, -2, -2, -2, -2, -2, -2, -2, -2
(list; table; graph; listen)
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OFFSET
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0,4
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COMMENT
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Inverse of A113678. Sequence array of A113679. Row sums are 3-2n-2*0^n. Diagonal sums are 1-n.
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FORMULA
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Number triangle T(n, k)=if(k<=n, C(0, n-k)+2*C(1, n-k)-2, 0).
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EXAMPLE
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Triangle begins
1;
0, 1;
-2, 0, 1;
-2, -2, 0, 1;
-2, -2, -2, 0, 1;
-2, -2, -2, -2, 0, 1;
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CROSSREFS
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Sequence in context: A118407 A101663 A062169 this_sequence A128187 A133121 A091602
Adjacent sequences: A113677 A113678 A113679 this_sequence A113681 A113682 A113683
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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), Nov 04 2005
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