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Search: id:A079675
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| A079675 |
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a(1)=1; a(n)=sum(u=1,n-1,sum(v=1,u,sum(w=1,v,sum(x=1, w,sum(y=1,x,a(y)))))). |
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+0
2
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| 1, 1, 6, 26, 106, 431, 1757, 7168, 29244, 119305, 486716, 1985603, 8100456, 33046585, 134816705, 549997641, 2243767969, 9153665985, 37343255690, 152345382480, 621507555626, 2535499503900, 10343812679475, 42198572937400
(list; graph; listen)
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OFFSET
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1,3
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COMMENT
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Row sums of Riordan array (1,1/(1-x)^5). A quintisection of A003520. - Paul Barry (pbarry(AT)wit.ie), Feb 02 2006
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FORMULA
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a(1)=1, a(2)=1, a(3)=6, a(4)=26, a(5)=106, a(6)=431; for n>=7, a(n)=5*u(n-1)-4*u(n-2)+u(n-3)+b(n) where b(n) is the 6 periodic sequence (0, 1, 1, 0, -1, -1)
G.f.: (1-x)^5/((1-x)^5-x); a(n)=sum{k=0..n, binomial(5n-4k-1,k)}; - Paul Barry (pbarry(AT)wit.ie), Feb 02 2006
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CROSSREFS
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Cf. A055991, A052529, A001906.
Sequence in context: A037545 A027996 A020989 this_sequence A113991 A124465 A046647
Adjacent sequences: A079672 A079673 A079674 this_sequence A079676 A079677 A079678
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KEYWORD
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nonn
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AUTHOR
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Benoit Cloitre (benoit7848c(AT)orange.fr), Jan 26 2003
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