%I A113989
%S A113989 1,2,4,8,18,46,136,464,1818,8122,41076,233472,1480946,10412590,80634432,
%T A113989 683674832,6312152354,63144706754,681317547508,7896054343496,
%U A113989 97919789763074,1294863406981790,18200820837825480,271147632138373600
%N A113989 Column 0 of triangle A113988, which is the matrix square of A113983: 
               a(n) = [A113983^2](n,0).
%F A113989 a(n) = A113984(n+1) - 1. a(n) = a(n-2) + A113990(n-2) + 2 for n>=2.
%o A113989 (PARI) {a(n)=local(A,B);A=Mat(1);for(m=2,n+1,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^2)[n+1,1]}
%Y A113989 Cf. A113988, A113990 (column 1), A113991 (column 2), A113992 (column 
               3); A113984, A113983, A113993.
%Y A113989 Sequence in context: A125809 A000117 A006771 this_sequence A126757 A034766 
               A099785
%Y A113989 Adjacent sequences: A113986 A113987 A113988 this_sequence A113990 A113991 
               A113992
%K A113989 nonn
%O A113989 0,2
%A A113989 Paul D. Hanna (pauldhanna(AT)juno.com), Nov 12 2005