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%I #3 Mar 30 2012 18:36:58
%S 1,1,4,22,146,1131,10120,104015,1220957,16253289,243450538,4070466861,
%T 75393600728,1536160429870,34213493149270,828220957918213,
%U 21680478452572459,610911511290740374,18453811792850260925
%N Column 3 of triangle A121391, where column k of T=A121391 equals column k of T^(k+1) shift down 1 row.
%C Also equal to column 3 (shifted 1 place) of the matrix 4th power of triangle A121391.
%o (PARI) {a(n)=local(A=Mat(1), B); for(m=1, n+4, B=matrix(m, m); for(i=1, m, for(j=1, i, if(j==i,B[i, j]=1, B[i, j]=(A^j)[i-1, j]); )); A=B); return(A[n+4, 4])}
%Y Cf. A121391 (triangle), A121392 (column 1), A121393 (column 2).
%K nonn
%O 0,3
%A _Paul D. Hanna_, Jul 27 2006
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