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Column 2 of triangle A123305.
7

%I #5 Jun 11 2015 14:06:59

%S 1,3,18,144,1422,16848,235458,3827628,71466174,1515031920,36091609434,

%T 957367079244,28050237910926,901359663633000,31567805908329330,

%U 1198307340146774844,49060139971072916142,2156816501291429473248

%N Column 2 of triangle A123305.

%C Triangle T=A123305 is defined by: (column k of T) = (k+1)*(column k of T^2) shifted to have an initial '1'; thus this sequence shifted left equals 3 times column 2 of T^2 (matrix square of A123305).

%Y Cf. A123305, A123306, A123307, A123309, A123310, A123311.

%K nonn

%O 0,2

%A _Paul D. Hanna_, Sep 24 2006