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Search: id:A124753
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| A124753 |
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a(3n+k)=(k+1)*binomial(4n+k,n)/(3n+k+1), k=0,..2. |
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+0
3
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| 1, 1, 1, 1, 2, 3, 4, 9, 15, 22, 52, 91, 140, 340, 612, 969, 2394, 4389, 7084, 17710, 32890, 53820, 135720, 254475, 420732, 1068012, 2017356, 3362260, 8579560, 16301164, 27343888, 70068713, 133767543, 225568798, 580034052
(list; graph; listen)
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OFFSET
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0,5
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COMMENT
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Row sums of Riordan array (1,x(1-x^3))^(-1). Also row sums of A124752. a(3n)=A002293(n), a(3n+1)=A069271(n), A(3n+2)=A006632(n).
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FORMULA
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a(n)=((mod(n,3)+1)*C(4*floor(n/3)+mod(n,3),floor(n/3))/(3*floor(n/3)+1+mod(n,3))); - Paul Barry (pbarry(AT)wit.ie), Dec 14 2006
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CROSSREFS
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Cf. A118968.
Sequence in context: A033076 A121431 A084080 this_sequence A049909 A096781 A119721
Adjacent sequences: A124750 A124751 A124752 this_sequence A124754 A124755 A124756
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KEYWORD
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easy,nonn
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Nov 06 2006
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