cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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.

Original entry on oeis.org

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

Views

Author

Paul D. Hanna, Sep 16 2004

Keywords

Comments

Column 2 forms A098543. Row sums form A098544. The absolute value of the matrix inverse equals A098539.

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.
		

Crossrefs

Cf. A098543, A098544, A098539 (absolute inverse).

Programs

  • 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]

Formula

T(n+1, 1) = 2 for n>0; T(n+1, n) = 2^n, T(n+2, n) = 4^n - 2^n for n>=0. Matrix square: [T^2](n, k) = T(n+1, k+1). Matrix inverse: [T^-1](n, k) = (-1)^(n-k)*A098539(n, k). Matrix square inverse: [T^-2](n, k) = (-1)^(n-k)*A098539(n+1, k+1).