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Search: id:A109955
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| A109955 |
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Number triangle binomial(n+2k,3k). |
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+0
2
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| 1, 1, 1, 1, 4, 1, 1, 10, 7, 1, 1, 20, 28, 10, 1, 1, 35, 84, 55, 13, 1, 1, 56, 210, 220, 91, 16, 1, 1, 84, 462, 715, 455, 136, 19, 1, 1, 120, 924, 2002, 1820, 816, 190, 22, 1, 1, 165, 1716, 5005, 6188, 3876, 1330, 253, 25, 1, 1, 220, 3003, 11440, 18564, 15504, 7315, 2024
(list; table; graph; listen)
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OFFSET
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0,5
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COMMENT
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Riordan array (1/(1-x),x/(1-x)^3). Inverse array is A109956. Row sums are A052544. Diagonal sums are A034943(n+1).
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FORMULA
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Number triangle T(n, k)=binomial(n+2k, 3k)
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EXAMPLE
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Rows begin
1;
1,1;
1,4,1;
1,10,7,1;
1,20,28,10,1;
1,35,84,55,13,1;
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CROSSREFS
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Sequence in context: A056647 A056057 A016520 this_sequence A089447 A082680 A056939
Adjacent sequences: A109952 A109953 A109954 this_sequence A109956 A109957 A109958
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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), Jul 06 2005
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