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A138177
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Triangle T(n,k) read by rows: number of k X k symmetric matrices with nonnegative integer entries and without zero rows or columns such that sum of all entries is equal to n, n>=1, 1<=k<=n.
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1
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1, 1, 2, 1, 4, 4, 1, 7, 15, 10, 1, 10, 36, 52, 26, 1, 14, 74, 176, 190, 76, 1, 18, 132, 460, 810, 696, 232, 1, 23, 222, 1060, 2705, 3756, 2674, 764, 1, 28, 347, 2180, 7565, 15106, 17262, 10480, 2620, 1, 34, 525, 4204, 19013, 51162, 83440, 80816, 42732, 9496, 1, 40
(list; table; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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EXAMPLE
| 1
1,2
1,4,4
1,7,15,10
1,10,36,52,26
1,14,74,176,190,76
1,18,132,460,810,696,232
1,23,222,1060,2705,3756,2674,764
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CROSSREFS
| Cf. (row sums) A138178, A135589, A135588.
Sequence in context: A154558 A008572 A118976 * A101559 A122438 A156708
Adjacent sequences: A138174 A138175 A138176 * A138178 A138179 A138180
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KEYWORD
| nonn,tabl
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AUTHOR
| Vladeta Jovovic (vladeta(AT)eunet.rs), Mar 03 2008
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