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%I #3 Mar 30 2012 17:34:19
%S 0,1,3,20,189,2348,36165,665058,14219373,346585416,9485780589,
%T 288039271830,9609639556869,349403495309244,13751661631299813,
%U 582461437448921562,26417039609670967485,1277337284263389184272
%N a(n)= 3*(n-1)*a(n-1) +(n-1)*a(n-2), with a(0)=1, a(1)=1.
%C This is also the (2,2) element of the product matrix after multiplying the unit matrix from the
%C left by the matrices (0,1;j-1,3j-3) in the order j=2 to n.
%t M[n_] := {{0, 1}, {(n - 1), 3*(n - 1)}} v[1] = {0, 1} v[n_] := v[n] = M[n].v[n - 1] a = Table[Abs[v[n][[1]]], {n, 1, 25}]
%Y Cf. A000166.
%K nonn,easy
%O 0,3
%A _Roger L. Bagula_, Jun 15 2005
%E Definition replaced by recurrence by the Associate Editors of the OEIS, Sep 28 2009