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Search: id:A026725
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| A026725 |
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Triangular array T read by rows: T(n,0)=T(n,n)=1 for n >= 0; for n >= 2 and 1<=k<=n-1, T(n,k)=T(n-1,k-1)+T(n-2,k-1)+T(n-1,k) if n is odd and k=(n-1)/2, else T(n,k)=T(n-1,k-1)+T(n-1,k). |
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+0
26
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| 1, 1, 1, 1, 2, 1, 1, 4, 3, 1, 1, 5, 7, 4, 1, 1, 6, 16, 11, 5, 1, 1, 7, 22, 27, 16, 6, 1, 1, 8, 29, 65, 43, 22, 7, 1, 1, 9, 37, 94, 108, 65, 29, 8, 1, 1, 10, 46, 131, 267, 173, 94, 37, 9, 1, 1, 11, 56, 177, 398, 440, 267, 131, 46, 10, 1, 1, 12, 67, 233
(list; table; graph; listen)
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OFFSET
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1,5
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LINKS
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Rob Arthan, Comments on A026674, A026725, A026670
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FORMULA
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T(n, k) = number of paths from (0, 0) to (n-k, k) in directed graph having vertices (i, j) and edges (i, j)-to-(i+1, j) and (i, j)-to-(i, j+1) for i, j >= 0, and edges (i, i+1)-to-(i+1, i+2) for i >= 0.
Comment from Rick L. Shepherd (rshepherd2(AT)hotmail.com), Aug 05 2002: Probably this should be changed to "and edges (i+1, i)-to-(i+2, i+1) for i >= 0."
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CROSSREFS
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Cf. A026674.
Sequence in context: A122517 A123199 A112096 this_sequence A026758 A130523 A034363
Adjacent sequences: A026722 A026723 A026724 this_sequence A026726 A026727 A026728
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KEYWORD
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nonn,tabl
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AUTHOR
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Clark Kimberling (ck6(AT)evansville.edu)
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