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%I #6 Jun 13 2017 23:37:39
%S 1,3,7,17,45,135,463,1817,8121,41075,233471,1480945,10412589,80634431,
%T 683674831,6312152353,63144706753,681317547507,7896054343495,
%U 97919789763073,1294863406981789,18200820837825479,271147632138373599
%N Column 2 of triangle A113983; also a(n) = A113983(n+1,1) + [A113983^2](n,1).
%F a(n) = [A113983^2](n, 0) + [A113983^3](n-1, 0) = A113989(n) + A113994(n-1).
%o (PARI) a(n)=local(A,B);A=Mat(1);for(m=2,n+3,B=matrix(m,m); for(i=1,m, for(j=1,i,if(i<3 || j==1 || j==i,B[i,j]=1, B[i,j]=A[i-1,j-1]+(A^2)[i-2,j-1]);));A=B);A[n+3,3]
%Y Cf. A113983, A113984 (column 1), A113986 (column 3), A113987 (column 4).
%K nonn
%O 0,2
%A _Paul D. Hanna_, Nov 12 2005
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