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A051125 Table T(n,k) = max{n,k} read by antidiagonals (n >= 1, k >= 1).

Original entry on oeis.org

1, 2, 2, 3, 2, 3, 4, 3, 3, 4, 5, 4, 3, 4, 5, 6, 5, 4, 4, 5, 6, 7, 6, 5, 4, 5, 6, 7, 8, 7, 6, 5, 5, 6, 7, 8, 9, 8, 7, 6, 5, 6, 7, 8, 9, 10, 9, 8, 7, 6, 6, 7, 8, 9, 10, 11, 10, 9, 8, 7, 6, 7, 8, 9, 10, 11, 12, 11, 10, 9, 8, 7, 7, 8, 9, 10, 11, 12, 13, 12, 11, 10, 9, 8, 7, 8, 9, 10, 11, 12, 13, 14, 13
Offset: 1

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Comments

Antidiagonal sums = A006578. - Reinhard Zumkeller, Nov 17 2011

Examples

			Table begins
  1, 2, 3, 4, 5, ...
  2, 2, 3, 4, 5, ...
  3, 3, 3, 4, 5, ...
  4, 4, 4, 4, 5, ...
  ...
		

Crossrefs

Equals A003984(n) + 1.

Programs

  • GAP
    Flat(List([1..15], n-> List([1..n], k-> Maximum(n-k+1,k) ))); # G. C. Greubel, Jul 23 2019
  • Magma
    [Max(n-k+1,k): k in [1..n], n in [1..15]]; // G. C. Greubel, Jul 23 2019
    
  • Maple
    seq(seq(max(r,d+1-r),r=1..d),d=1..15); # Robert Israel, Jul 22 2016
  • Mathematica
    Flatten[Table[Max[n-k+1, k], {n, 13}, {k, n, 1, -1}]] (* Alonso del Arte, Nov 17 2011 *)
  • PARI
    T(n,k) = max(n,k) \\ Charles R Greathouse IV, Feb 07 2017
    
  • Sage
    [[max(n-k+1,k) for k in (1..n)] for n in (1..15)] # G. C. Greubel, Jul 23 2019
    

Formula

From Robert Israel, Jul 22 2016: (Start)
G.f. as table: G(x,y) = x*y*(1-3*x*y+x*y^2+x^2*y)/((1-x*y)*(1-x)^2*(1-y)^2).
G.f. flattened: (1-x)^(-2)*(x^2 + Sum_{j >= 0} x^(2*j^2) *(x+x^2 -2*x^(j+2)-2*x^(-j+2)+2*x^(2*j+2))). (End)

Extensions

More terms from Robert Lozyniak