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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.

A098495 Array T(r,c) read by antidiagonals: values of triangle A098493 interpreted as polynomials, r >= 0.

Original entry on oeis.org

1, 1, 0, 1, -1, -1, 1, -2, -1, -1, 1, -3, 1, 1, 0, 1, -4, 5, 1, 1, 1, 1, -5, 11, -7, -2, -1, 1, 1, -6, 19, -29, 9, 1, -1, 0, 1, -7, 29, -71, 76, -11, 1, 1, -1, 1, -8, 41, -139, 265, -199, 13, -2, 1, -1, 1, -9, 55, -239, 666, -989, 521, -15, 1, -1, 0, 1, -10, 71, -377, 1393, -3191, 3691, -1364, 17, 1, -1, 1, 1, -11, 89, -559
Offset: 0

Views

Author

Ralf Stephan, Sep 12 2004

Keywords

Examples

			Array begins
  1,  0, -1,  -1,   0,    1,    1,   0, -1, ...
  1, -1, -1,   1,   1,   -1,   -1,   1,  1, ...
  1, -2,  1,   1,  -2,    1,    1,  -2,  1, ...
  1, -3,  5,  -7,   9,  -11,   13, -15, ...
  1, -4, 11, -29,  76, -199,  521, ...
  1, -5, 19, -71, 265, -989, 3691, ...
  ...
		

Crossrefs

See A094954 (with negative k) for negative r and more formulas and programs.
Rows include (-1)^c times A005408, A002878, A001834, A030221, A002315. Columns include A028387. Antidiagonal sums are in A098496.

Programs

  • Mathematica
    T[r_, 1] := 1; T[r_, 2] := -r - 1; T[r_, c_] := -r*T[r, c - 1] - T[r, c - 2]; Flatten[ Table[ T[n - i, i], {n, 0, 11}, {i, n + 1}]] (* Robert G. Wilson v, May 10 2005 *)
  • PARI
    { t(r,c)=if(c>r||c<0||r<0,0,if(c>=r-1,(-1)^r*if(c==r,1,-c),if(r==1,0,if(c==0,t(r-1,0)-t(r-2,0),t(r-1,c)-t(r-2,c)-t(r-1,c-1))))) }
    T(r,c)=sum(i=0,c,t(c,i)*r^i);
    matrix(5,5,n,k,T(n-1,k-1))

Formula

Recurrence: T(r, 1) = 1, T(r, 2) = -r-1, T(r, c) = -rT(r, c-1) - T(r, c-2). (Corrected Oct 19 2004)

Extensions

More terms from Robert G. Wilson v, May 10 2005