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 A080858 Triangle read by rows: T(n,k), n >=1, 0 <= k <= C(n,k), = number of n X n symmetric positive definite matrices with 2's on the main diagonal and 1's and 0's elsewhere and with w 1's above the diagonal. 8

%I

%S 1,1,1,1,3,3,1,1,6,15,20,12,6,1,1,10,45,120,190,192,140,80,30,10,1

%N Triangle read by rows: T(n,k), n >=1, 0 <= k <= C(n,k), = number of n X n symmetric positive definite matrices with 2's on the main diagonal and 1's and 0's elsewhere and with w 1's above the diagonal.

%H <a href="/index/Mat#binmat">Index entries for sequences related to binary matrices</a>

%e 1; 1,1; 1,3,3,1; 1,6,15,20,12,6,1; ...

%Y Rows sums give A085657. A085656(n) = Sum_{k=0..C(n, 2)} 2^k*T(n, k).

%K nonn,tabf

%O 1,5

%A _N. J. A. Sloane_, Jul 13 2003

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Last modified August 6 18:25 EDT 2020. Contains 336256 sequences. (Running on oeis4.)