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A101551
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C(n-2,2)+C(n-5,5)+...+C(n-(3*floor((n-3)/3)+2),3*floor((n-3)/3)+2).
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3
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0, 0, 0, 0, 1, 3, 6, 10, 15, 21, 29, 42, 66, 111, 192, 330, 554, 906, 1452, 2303, 3651, 5826, 9382, 15225, 24807, 40431, 65748, 106584, 172321, 278184, 448980, 725140, 1172412, 1897380, 3072365, 4975551, 8055918, 13038606, 21096027, 34125561
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,6
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LINKS
| Index to sequences with linear recurrences with constant coefficients, signature (3,-3,1,0,0,1)
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FORMULA
| G.f.: x^4/((1-x)^3-x^6) = -x^4/ ( (x^2+x-1)*(x^4-x^3+2*x^2-2*x+1) ).
a(n)=sum{k=0..n, if(mod(k+1, 3)=0, C(n-k, k), 0)}.
a(n+2)=sum{k=0..floor(n/6), binomial(n-3k, 3k+2)}. - Paul Barry (pbarry(AT)wit.ie), Jan 13 2005
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CROSSREFS
| Cf. A024490, A101552.
Sequence in context: A115650 A025745 A175724 * A051166 A188278 A188279
Adjacent sequences: A101548 A101549 A101550 * A101552 A101553 A101554
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KEYWORD
| easy,nonn
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Dec 06 2004
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