A098542 Triangle T, read by rows, such that the matrix square shifts T left one column and up one row, with T(0,0)=T(1,0)=1 and T(n,0)=0 for n>1 and T(n,n)=1 for n>=0.
1, 1, 1, 0, 2, 1, 0, 2, 4, 1, 0, 2, 12, 8, 1, 0, 2, 44, 56, 16, 1, 0, 2, 236, 504, 240, 32, 1, 0, 2, 2028, 6776, 4720, 992, 64, 1, 0, 2, 29164, 146552, 139120, 40672, 4032, 128, 1, 0, 2, 719340, 5314680, 6583152, 2500832, 337344, 16256, 256, 1, 0, 2, 30943724
Offset: 0
Examples
Rows of T begin: [1], [1,1], [0,2,1], [0,2,4,1], [0,2,12,8,1], [0,2,44,56,16,1], [0,2,236,504,240,32,1], [0,2,2028,6776,4720,992,64,1], [0,2,29164,146552,139120,40672,4032,128,1], [0,2,719340,5314680,6583152,2500832,337344,16256,256,1],... Rows of T^2 begin: [1], [2,1], [2,4,1], [2,12,8,1], [2,44,56,16,1], [2,236,504,240,32,1],... showing that T shifts left and up under matrix square. The matrix inverse of T begins: [1], [ -1,1], [2,-2,1], [ -6,6,-4,1], [26,-26,20,-8,1], [ -166,166,-140,72,-16,1],... the absolute value of which equals triangle A098539.
Programs
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PARI
T(n,k)=local(A,B);A=matrix(1,1);A[1,1]=1;for(m=2,n+1,B=matrix(m,m); for(i=1,m, for(j=1,i,if(i<3 || j==i || j>m-1,B[i,j]=1,if(j==1, B[i,j]=(A^0)[i-1,1],B[i,j]=(A^2)[i-1,j-1]));));A=B);A[n+1,k+1]
Comments