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.

A085143 Triangle table from number wall of reversion of Fibonacci numbers.

Original entry on oeis.org

1, -1, -1, -1, -1, -1, 1, 0, 2, 1, 1, -2, 4, 3, 1, -1, 3, -11, -5, -5, -1, -1, -1, -34, 10, -20, -8, -1, 1, 11, 106, -116, 96, 44, 13, 1, 1, 15, 368, -328, 716, 86, 125, 21, 1, -1, 13, -1324, -1344, -5634, 1866, -1063, -316, -34, -1, -1, 77, -4811, -17235
Offset: 1

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Author

Michael Somos, Jun 19 2003

Keywords

Examples

			T(4,2)=0 since det([0,0,1,-1; 0,1,-1,0; 1,-1,0,2; -1,0,2,-3])=0.
    1
   -1    -1
   -1    -1    -1
    1     0     2     1
    1    -2     4     3     1
   -1     3   -11    -5    -5    -1
   -1    -1   -34    10   -20    -8    -1
    1    11   106  -116    96    44    13     1
    1    15   368  -328   716    86   125    21     1
   -1    13 -1324 -1344 -5634  1866 -1063  -316   -34    -1
		

Crossrefs

Cf. A007440.

Programs

  • Maple
    A085143 := proc(n,k)
        local A,r,c ;
        A := Matrix(n,n) ;
        for r from 1 to n do
        for c from 1 to n do
            A[r,c] :=  A007440(r+c-1+k-n) ;
        end do:
        end do:
        Determinant(A) ;
    end proc:
    seq(seq(A085143(n,k),k=1..n),n=1..12) ; # R. J. Mathar, Jul 21 2023
  • PARI
    {f(n)=polcoeff((-1-x+sqrt(1+2*x+5*x^2+x^2*O(x^n)))/(2*x),n)} \\ A007440
    {T(n,k)=matdet(matrix(n,n,i,j,f(i+j-1+k-n)))}

Formula

T(n, k) = det(f(i+j-1+k-n)_{i, j=1..n}) where f(n)=A007440(n).
T(n, k) = (-1)^[(n+k-1)/2]*T(k-1, n-1) if 1<=k<=n.