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A357141
Number of n X n triangular matrices with nonnegative integer entries and without zero rows or columns such that sum of all entries is equal to 2n.
2
1, 1, 6, 71, 1433, 44443, 1968580, 118159971, 9240555677, 913352224942, 111374887418013, 16428282185046946, 2883740893056526715, 594152447495864629867, 142006380268368661423424, 38973735372090120549251580, 12174162204364698538764222978, 4294569227671480526607187583713
OFFSET
0,3
FORMULA
a(n) = A137251(2n,n).
CROSSREFS
Cf. A137251.
Sequence in context: A218676 A127135 A187651 * A005981 A024272 A167813
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Sep 14 2022
STATUS
approved