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Search: id:A115951
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| A115951 |
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Expansion of 1/sqrt(1-4xy-4x^2*y). |
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+0
2
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| 1, 0, 2, 0, 2, 6, 0, 0, 12, 20, 0, 0, 6, 60, 70, 0, 0, 0, 60, 280, 252, 0, 0, 0, 20, 420, 1260, 924, 0, 0, 0, 0, 280, 2520, 5544, 3432, 0, 0, 0, 0, 70, 2520, 13860, 24024, 12870, 0, 0, 0, 0, 0, 1260, 18480, 72072, 102960, 48620, 0, 0, 0, 0, 0, 252, 13860, 120120, 360360
(list; table; graph; listen)
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OFFSET
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0,3
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COMMENT
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Row sums are A006139. Diagonal sums are A115962.
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FORMULA
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Number triangle T(n,k)=C(2k,k)*C(k,n-k).
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EXAMPLE
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Triangle begins
1,
0, 2,
0, 2, 6,
0, 0, 12, 20,
0, 0, 6, 60, 70,
0, 0, 0, 60, 280, 252,
0, 0, 0, 20, 420, 1260, 924
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CROSSREFS
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Sequence in context: A033721 A033739 A033733 this_sequence A057607 A139213 A033727
Adjacent sequences: A115948 A115949 A115950 this_sequence A115952 A115953 A115954
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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), Mar 14 2006
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