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Triangle T(n,k) = A042948(n-k+1) read by rows, 0<=k<=n.
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%I #5 Mar 30 2012 17:25:11

%S 1,4,1,5,4,1,8,5,4,1,9,8,5,4,1,12,9,8,5,4,1,13,12,9,8,5,4,1,16,13,12,

%T 9,8,5,4,1

%N Triangle T(n,k) = A042948(n-k+1) read by rows, 0<=k<=n.

%F The triangle is extracted from the product of lower triangular matrices (with the rest of the terms all zeros): G * R (or R * G); G = [1; 3, 1; 1, 3, 1; 3, 1, 3, 1;...]; R = [1; 1, 1; 1, 1, 1;...].

%e The first few rows are:

%e 1;

%e 4, 1;

%e 5, 4, 1;

%e 8, 5, 4, 1;

%e 9, 8, 5, 4, 1;

%e ...

%Y Cf. A042948, A035608 (row sums), A104570, A104569, A074377.

%K nonn,tabl,easy

%O 0,2

%A _Gary W. Adamson_, Mar 16 2005