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Search: id:A101688
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| A101688 |
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Once 1, once 0, repeat, twice 1, twice 0, repeat, thrice 1, thrice 0... and so on. |
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+0
9
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| 1, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1
(list; table; graph; listen)
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OFFSET
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0,1
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COMMENT
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Triangle T read by rows: T(k,n)=1 if n>=ceil(k/2), 0 otherwise.
Square array A, read by antidiagonals: A(k,n)=1 if n>=k, 0 otherwise.
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FORMULA
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G.f.: 1/[(1-xy)(1-y)]. k-th row of array: x^(k-1)/(1-x).
T(n, k)=if(binomial(k, n-k)>0, 1, 0). - Paul Barry (pbarry(AT)wit.ie), Aug 23 2005
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EXAMPLE
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.1 1 1 1 1 1 1 1 1 ......... 1
.0 1 1 1 1 1 1 1 1 ........ 0 1
.0 0 1 1 1 1 1 1 1 ....... 0 1 1
.0 0 0 1 1 1 1 1 1 ...... 0 0 1 1
.0 0 0 0 1 1 1 1 1 ..... 0 0 1 1 1
.0 0 0 0 0 1 1 1 1 .... 0 0 0 1 1 1
.0 0 0 0 0 0 1 1 1 ... 0 0 0 1 1 1 1
.0 0 0 0 0 0 0 1 1 .. 0 0 0 0 1 1 1 1
.0 0 0 0 0 0 0 0 1 . 0 0 0 0 1 1 1 1 1
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CROSSREFS
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Row/antidiagonal sums are A008619. Cf. A079813.
Sequence in context: A127241 A087748 A117446 this_sequence A155031 A155029 A134540
Adjacent sequences: A101685 A101686 A101687 this_sequence A101689 A101690 A101691
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KEYWORD
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nonn,tabl
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AUTHOR
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Ralf Stephan, Dec 19 2004
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