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Row sums of triangle A098539, which shifts left one column under the matrix square.
2

%I #6 Jun 13 2017 22:13:25

%S 1,2,5,17,81,561,5905,98673,2715025,126550129,10211715985,

%T 1450856148081,367849450783633,168250359224212593,

%U 140078954639877776273,213886080203739816320113,602782564524824650717471633

%N Row sums of triangle A098539, which shifts left one column under the matrix square.

%o (PARI) a(n)=local(A,B,C,m);A=matrix(1,1);A[1,1]=1; for(m=2,n+1,B=A^2;C=matrix(m,m);for(j=1,m, for(k=1,j, if(j<3 || k==j || k>m-1,C[j,k]=1,if(k==1,C[j,k]=B[j-1,1],C[j,k]=B[j-1,k-1])); ));A=C);sum(i=1,n+1,A[n+1,i])

%Y Cf. A098539, A098541.

%K nonn

%O 0,2

%A _Paul D. Hanna_, Sep 13 2004