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A083029
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Triangle read by rows: T(n,k), n >=1, 0 <= k <= C(n,k), = number of n X n symmetric positive semi-definite matrices with 2's on the main diagonal and 1's and 0's elsewhere and with k 1's above the diagonal.
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9
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1, 1, 1, 1, 3, 3, 1, 1, 6, 15, 20, 15, 6, 1, 1, 10, 45, 120, 210, 192, 200, 90, 45, 10, 1
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,5
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LINKS
| Index entries for sequences related to binary matrices
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EXAMPLE
| 1;
1,1;
1,3,3,1;
1,6,15,20,15,6,1;
...
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CROSSREFS
| Rows sums give A085658.
A038379(n) = Sum_{k=0..C(n, 2)} 2^k*T(n, k).
A084546 is an upper bound.
Sequence in context: A144163 A080858 A144228 * A084546 A174116 A026515
Adjacent sequences: A083026 A083027 A083028 * A083030 A083031 A083032
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KEYWORD
| nonn,tabf,more
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Jul 13 2003
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