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%I #3 Mar 30 2012 18:36:46
%S 0,1,4,31,343,4855,83209,1670743,38436673,996825703,28778874481,
%T 915636860023,31837734460129,1201360385000071,48899006799783889,
%U 2135779996980897175,99646497213608842561,4946194601237466540967
%N Column 0 of A107724, which is the matrix logarithm of triangle A107719.
%o (PARI) {a(n)=local(L,M=matrix(n+1,n+1,m,j,if(m>=j,if(m==j,1,if(m==j+1,-3*j, polcoeff(1/sum(i=0,m-j,prod(r=0,i-1,3*r+1)*x^i)+O(x^m),m-j)))))^-1); L=sum(i=1,#M,(-1)^(i-1)*(M-M^0)^i/i);return(if(n<0,0,L[n+1,1]/3))}
%Y Cf. A107717, A107719, A107724.
%K nonn
%O 0,3
%A _Paul D. Hanna_, May 30 2005
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