A317497
identification: the entry's rule defines the sequence for every index; tail: the sequence is the entry's tail after some prefix rows; match_*: finite agreement only.
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A317497: Triangle T(n,k) = 3*T(n-1,k) + T(n-3,k-1) for k = 0..floor(n/3) with T(0,0) = 1 and T(n,k) = 0 for n or k < 0, read by rows.
(identification, match triangle)
A102547 → x ↦ (1/27)x1 · 3 · 9 · 27, 1 … row sums 1, 3, 9, 28, 87, 270, 838, 2601, …