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A083029 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. 9
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; text; internal format)
OFFSET

1,5

LINKS

Table of n, a(n) for n=1..25.

Index entries for sequences related to binary matrices

EXAMPLE

1;

1,1;

1,3,3,1;

1,6,15,20,15,6,1;

...

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 A288266 A174116

Adjacent sequences:  A083026 A083027 A083028 * A083030 A083031 A083032

KEYWORD

nonn,tabf,more

AUTHOR

N. J. A. Sloane, Jul 13 2003

STATUS

approved

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Last modified January 16 23:44 EST 2019. Contains 319206 sequences. (Running on oeis4.)