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Search: id:A125693
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| A125693 |
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Riordan array ((1-x)/(1-3x),x(1-x)/(1-3x)). |
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+0
2
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| 1, 2, 1, 6, 4, 1, 18, 16, 6, 1, 54, 60, 30, 8, 1, 162, 216, 134, 48, 10, 1, 486, 756, 558, 248, 70, 12, 1, 1458, 2592, 2214, 1168, 410, 96, 14, 1, 4374, 8748, 8478, 5160, 2150, 628, 126, 16, 1, 13122, 29160, 31590, 21744
(list; table; graph; listen)
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OFFSET
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0,2
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COMMENT
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Row sums are A001835(n+1). Diagonal sums are A030186. Inverse is A125694. Equal to product of A007318 and A073370.
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FORMULA
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Number triangle T(n,k)=sum{j=0..k+1, C(k+1,j)C(n-j,n-k-j)(-1)^j*3^(n-k-j)}
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EXAMPLE
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Triangle begins
1,
2, 1,
6, 4, 1,
18, 16, 6, 1,
54, 60, 30, 8, 1,
162, 216, 134, 48, 10, 1
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CROSSREFS
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Sequence in context: A112360 A118040 A073387 this_sequence A094527 A054335 A110681
Adjacent sequences: A125690 A125691 A125692 this_sequence A125694 A125695 A125696
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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), Nov 30 2006
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