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Search: id:A117389
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| A117389 |
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A skew Delannoy number triangle read by rows. |
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+0
1
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| 1, 0, 1, 0, 1, 1, 0, 0, 3, 1, 0, 0, 1, 5, 1, 0, 0, 0, 5, 7, 1, 0, 0, 0, 1, 13, 9, 1, 0, 0, 0, 0, 7, 25, 11, 1, 0, 0, 0, 0, 1, 25, 41, 13, 1, 0, 0, 0, 0, 0, 9, 63, 61, 15, 1, 0, 0, 0, 0, 0, 1, 41, 129, 85, 17, 1
(list; table; graph; listen)
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OFFSET
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0,9
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COMMENT
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Row sums are the trinomial numbers A000073(n+2). Diagonal sums are A079973.
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FORMULA
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Number triangle T(n,k)=[k<=n]*sum{j=0..2k-n, C(2k-n,j)C(n-k,j)2^j}; T(n,k)=sum{j=0..2k-n, C(2k-n,j)C(n-k,n-k-j)2^j};
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EXAMPLE
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Triangle begins
1,
0, 1,
0, 1, 1,
0, 0, 3, 1,
0, 0, 1, 5, 1,
0, 0, 0, 5, 7, 1,
0, 0, 0, 1, 13, 9, 1,
0, 0, 0, 0, 7, 25, 11, 1
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CROSSREFS
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Cf. A008288.
Adjacent sequences: A117386 A117387 A117388 this_sequence A117390 A117391 A117392
Sequence in context: A128208 A094544 A062734 this_sequence A122083 A098158 A110319
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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 11 2006
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