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Search: id:A122919
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| A122919 |
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Inverse of Riordan array (1/(1+x+x^2),x/(1+x)^2). |
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+0
3
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| 1, 1, 1, 3, 3, 1, 9, 10, 5, 1, 28, 34, 21, 7, 1, 90, 117, 83, 36, 9, 1, 297, 407, 319, 164, 55, 11, 1, 1001, 1430, 1209, 702, 285, 78, 13, 1, 3432, 5070, 4550, 2898, 1350, 454, 105, 15, 1, 11934, 18122, 17068, 11696, 6052
(list; table; graph; listen)
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OFFSET
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0,4
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COMMENT
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Row sums are A097613. Diagonal sums are A122920. Inverse of A122917.
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FORMULA
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Riordan array ((1-3x+2x^2-(1-x)sqrt(1-4x))/(2x^2),(1-2x-sqrt(1-4x))/(2x))
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EXAMPLE
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Triangle begins
1,
1, 1,
3, 3, 1,
9, 10, 5, 1,
28, 34, 21, 7, 1,
90, 117, 83, 36, 9, 1,
297, 407, 319, 164, 55, 11, 1,
1001, 1430, 1209, 702, 285, 78, 13, 1
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CROSSREFS
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Sequence in context: A078033 A108075 A084145 this_sequence A157401 A143911 A131889
Adjacent sequences: A122916 A122917 A122918 this_sequence A122920 A122921 A122922
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KEYWORD
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easy,nonn,tabl
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Sep 19 2006
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