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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.

A100326 Triangle, read by rows, where row n equals the inverse binomial of column n of square array A100324, which lists the self-convolutions of SHIFT(A003169).

Original entry on oeis.org

1, 1, 1, 3, 4, 1, 14, 20, 7, 1, 79, 116, 46, 10, 1, 494, 736, 311, 81, 13, 1, 3294, 4952, 2174, 626, 125, 16, 1, 22952, 34716, 15634, 4798, 1088, 178, 19, 1, 165127, 250868, 115048, 36896, 9094, 1724, 240, 22, 1, 1217270, 1855520, 862607, 285689, 74687, 15629, 2561, 311, 25, 1
Offset: 0

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Author

Paul D. Hanna, Nov 17 2004

Keywords

Comments

The leftmost column equals A003169 shift one place right.
Each column k > 0 equals the convolution of the prior column and A003169.
Row sums form A100327.
The elements of the matrix inverse are T^(-1)(n,k) = (-1)^(n+k) * A158687(n,k). - R. J. Mathar, Mar 15 2013

Examples

			Rows begin:
        1;
        1,       1;
        3,       4,      1;
       14,      20,      7,      1;
       79,     116,     46,     10,     1;
      494,     736,    311,     81,    13,     1;
     3294,    4952,   2174,    626,   125,    16,    1;
    22952,   34716,  15634,   4798,  1088,   178,   19,   1;
   165127,  250868, 115048,  36896,  9094,  1724,  240,  22,  1;
  1217270, 1855520, 862607, 285689, 74687, 15629, 2561, 311, 25,  1;
  ...
First column forms A003169 shift right.
Binomial transform of row 3 forms column 3 of square A100324: BINOMIAL([14,20,7,1]) = [14,34,61,96,140,194,259,...].
Binomial transform of row 4 forms column 4 of square A100324: BINOMIAL([79,116,46,10,1]) = [79,195,357,575,860,1224,...].
		

Crossrefs

Cf. A003169, A100324, A100327 (row sums), A158687, A264717 (central terms).

Programs

  • Haskell
    import Data.List (transpose)
    a100326 n k = a100326_tabl !! n !! k
    a100326_row n = a100326_tabl !! n
    a100326_tabl = [1] : f [[1]] where
    f xss@(xs:_) = ys : f (ys : xss) where
    ys = y : map (sum . zipWith (*) (zs ++ [y])) (map reverse zss)
    y = sum $ zipWith (*) [1..] xs
    zss@((:zs):) = transpose $ reverse xss
    -- Reinhard Zumkeller, Nov 21 2015
    
  • Maple
    A100326 := proc(n,k)
        if k < 0 or k > n then
            0 ;
        elif n = 0 then
            1 ;
        elif k = 0 then
            A003169(n)
        else
            add(procname(i+1,0)*procname(n-i-1,k-1),i=0..n-k) ;
        end if;
    end proc: # R. J. Mathar, Mar 15 2013
  • Mathematica
    lim= 9; t[0, 0]=1; t[n_, 0]:= t[n, 0]= Sum[(k+1)*t[n-1,k], {k,0,n-1}]; t[n_, k_]:= t[n, k]= Sum[t[j+1, 0]*t[n-j-1, k-1], {j,0,n-k}]; Flatten[Table[t[n, k], {n,0,lim}, {k,0,n}]] (* Jean-François Alcover, Sep 20 2011 *)
  • PARI
    T(n,k)=if(n
    				
  • SageMath
    @CachedFunction
    def T(n,k): # T = A100326
        if (k<0 or k>n): return 0
        elif (k==n): return 1
        elif (k==0): return sum((j+1)*T(n-1,j) for j in range(n))
        else: return sum(T(j+1,0)*T(n-j-1,k-1) for j in range(n-k+1))
    flatten([[T(n,k) for k in range(n+1)] for n in range(13)]) # G. C. Greubel, Jan 30 2023

Formula

T(n, 0) = A003169(n) = Sum_{k=0..n-1} (k+1)*T(n-1, k) for n>0, with T(0, 0)=1.
T(n, k) = Sum_{i=0..n-k} T(i+1, 0)*T(n-i-1, k-1) for n > 0.
T(2*n, n) = A264717(n).
Sum_{k=0..n} T(n, k) = A100327(n).
G.f.: A(x, y) = (1 + G(x))/(1 - y*G(x)), where G(x) is the g.f. of A003169.
From G. C. Greubel, Jan 30 2023: (Start)
Sum_{k=0..n} (-1)^k*T(n, k) = A000007(n).
Sum_{k=0..n-1} (-1)^k*T(n, k) = A033999(n). (End)