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.

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A109906 A triangle based on A000045 and Pascal's triangle: T(n,m) = Fibonacci(n-m+1) * Fibonacci(m+1) * binomial(n,m).

Original entry on oeis.org

1, 1, 1, 2, 2, 2, 3, 6, 6, 3, 5, 12, 24, 12, 5, 8, 25, 60, 60, 25, 8, 13, 48, 150, 180, 150, 48, 13, 21, 91, 336, 525, 525, 336, 91, 21, 34, 168, 728, 1344, 1750, 1344, 728, 168, 34, 55, 306, 1512, 3276, 5040, 5040, 3276, 1512, 306, 55, 89, 550, 3060, 7560, 13650, 16128, 13650, 7560, 3060, 550, 89
Offset: 0

Views

Author

Roger L. Bagula and Gary W. Adamson, Aug 24 2008

Keywords

Comments

Row sums give A081057.

Examples

			Triangle T(n,k) begins:
   1;
   1,   1;
   2,   2,    2;
   3,   6,    6,    3;
   5,  12,   24,   12,     5;
   8,  25,   60,   60,    25,     8;
  13,  48,  150,  180,   150,    48,    13;
  21,  91,  336,  525,   525,   336,    91,   21;
  34, 168,  728, 1344,  1750,  1344,   728,  168,   34;
  55, 306, 1512, 3276,  5040,  5040,  3276, 1512,  306,  55;
  89, 550, 3060, 7560, 13650, 16128, 13650, 7560, 3060, 550, 89;
  ...
		

Crossrefs

Some other Fibonacci-Pascal triangles: A027926, A036355, A037027, A074829, A105809, A111006, A114197, A162741, A228074.

Programs

  • Haskell
    a109906 n k = a109906_tabl !! n !! k
    a109906_row n = a109906_tabl !! n
    a109906_tabl = zipWith (zipWith (*)) a058071_tabl a007318_tabl
    -- Reinhard Zumkeller, Aug 15 2013
  • Maple
    f:= n-> combinat[fibonacci](n+1):
    T:= (n, k)-> binomial(n, k)*f(k)*f(n-k):
    seq(seq(T(n, k), k=0..n), n=0..10);  # Alois P. Heinz, Apr 26 2023
  • Mathematica
    Clear[t, n, m] t[n_, m_] := Fibonacci[(n - m + 1)]*Fibonacci[(m + 1)]*Binomial[n, m]; Table[Table[t[n, m], {m, 0, n}], {n, 0, 10}]; Flatten[%]

Formula

T(n,m) = Fibonacci(n-m+1)*Fibonacci(m+1)*binomial(n,m).
T(n,k) = A058071(n,k) * A007318(n,k). - Reinhard Zumkeller, Aug 15 2013

Extensions

Offset changed by Reinhard Zumkeller, Aug 15 2013

A112899 A skew Pell-Pascal triangle.

Original entry on oeis.org

1, 0, 2, 0, 1, 5, 0, 0, 4, 12, 0, 0, 1, 14, 29, 0, 0, 0, 6, 44, 70, 0, 0, 0, 1, 27, 131, 169, 0, 0, 0, 0, 8, 104, 376, 408, 0, 0, 0, 0, 1, 44, 366, 1052, 985, 0, 0, 0, 0, 0, 10, 200, 1212, 2888, 2378, 0, 0, 0, 0, 0, 1, 65, 810, 3842, 7813, 5741, 0, 0, 0, 0, 0, 0, 12, 340, 3032, 11784
Offset: 0

Views

Author

Paul Barry, Oct 05 2005

Keywords

Comments

Main diagonal is A000129. Row sums are A002605. Column sums are A006190(n+1).
A skewed version of the Riordan array (1/(1-2x-x^2), x/(1-2x-x^2)), see A054456. - Philippe Deléham, Nov 21 2007
Triangle, read by rows, given by [0,1/2,-1/2,0,0,0,0,0,...] DELTA [2,1/2,-1/2,0,0,0,0,0,...] where DELTA is the operator defined in A084938. - Philippe Deléham, Jan 30 2010

Examples

			Rows begin:
  1;
  0,   2;
  0,   1,   5;
  0,   0,   4,  12;
  0,   0,   1,  14,  29;
  0,   0,   0,   6,  44,  70;
  0,   0,   0,   1,  27, 131, 169;
  0,   0,   0,   0,   8, 104, 376, 408;
		

Crossrefs

Cf. A111006, A112906. - Philippe Deléham, Jan 30 2010

Formula

G.f.: 1/(1-2*x*y*(1+x/2)-x^2*y^2).
T(n, k) = Sum_{j=0..floor((2*k-n)/2)} C(k-j, n-k)*C(2*k-n-j, j)*2^(2*k-2*j-n). [corrected by Jason Yuen, Jan 21 2025]
T(n, k) = 2*T(n-1, k-1) + T(n-2, k-1) + T(n-2, k-2).

A112883 A skew Jacobsthal-Pascal matrix.

Original entry on oeis.org

1, 0, 1, 0, 1, 3, 0, 0, 2, 5, 0, 0, 1, 7, 11, 0, 0, 0, 3, 16, 21, 0, 0, 0, 1, 12, 41, 43, 0, 0, 0, 0, 4, 34, 94, 85, 0, 0, 0, 0, 1, 18, 99, 219, 171, 0, 0, 0, 0, 0, 5, 60, 261, 492, 341, 0, 0, 0, 0, 0, 1, 25, 195, 678, 1101, 683, 0, 0, 0, 0, 0, 0, 6, 95, 576, 1692, 2426, 1365, 0, 0, 0, 0, 0
Offset: 0

Views

Author

Paul Barry, Oct 05 2005

Keywords

Comments

T(n,n) is A001045(n), row sums are A006130, column sums are A002605. Compare with [0,1,-1,0,0,..] DELTA [1,2,-2,0,0,...] where DELTA is the operator defined in A084938. A skewed version of the Riordan array (1/(1-x-2x^2),x/(1-x-2x^2)) (A073370).
Modulo 2, this sequence gives A106344. - Philippe Deléham, Dec 18 2008

Examples

			Rows begin
  1;
  0, 1;
  0, 1, 3;
  0, 0, 2, 5;
  0, 0, 1, 7, 11;
  0, 0, 0, 3, 16, 21;
  0, 0, 0, 1, 12, 41, 43;
  0, 0, 0, 0,  4, 34, 94,  85;
  0, 0, 0, 0,  1, 18, 99, 219, 171;
  0, 0, 0, 0,  0,  5, 60, 261, 492,  341;
  0, 0, 0, 0,  0,  1, 25, 195, 678, 1101, 683;
		

Crossrefs

Cf. A111006.

Formula

From Philippe Deléham: (Start)
G.f.: 1/(1-yx(1-x)-2x^2*y*2);
Number triangle T(n, k) = Sum_{j=0..2k-n} C(n-k+j, n-k)*C(j, 2k-n-j)*2^(2k-n-j);
T(n, k) = A073370(k, n-k); T(n, k) = T(n-1, k-1) + T(n-2, k-1) + 2*T(n-2, k-2). (End)

A236076 A skewed version of triangular array A122075.

Original entry on oeis.org

1, 0, 2, 0, 1, 3, 0, 0, 3, 5, 0, 0, 1, 7, 8, 0, 0, 0, 4, 15, 13, 0, 0, 0, 1, 12, 30, 21, 0, 0, 0, 0, 5, 31, 58, 34, 0, 0, 0, 0, 1, 18, 73, 109, 55, 0, 0, 0, 0, 0, 6, 54, 162, 201, 89, 0, 0, 0, 0, 0, 1, 25, 145, 344, 365, 144, 0, 0, 0, 0, 0, 0, 7, 85, 361
Offset: 0

Views

Author

Philippe Deléham, Jan 19 2014

Keywords

Comments

Triangle T(n,k), 0 <= k <= n, read by rows, given by (0, 1/2, -1/2, 0, 0, 0, 0, 0, 0, 0, ...) DELTA (2, -1/2, -1/2, 0, 0, 0, 0, 0, 0, 0, ...) where DELTA is the operator defined in A084938.
Subtriangle of the triangle A122950.

Examples

			Triangle begins:
  1;
  0,  2;
  0,  1,  3;
  0,  0,  3,  5;
  0,  0,  1,  7,  8;
  0,  0,  0,  4, 15, 13;
  0,  0,  0,  1, 12, 30, 21;
  0,  0,  0,  0,  5, 31, 58, 34;
		

Crossrefs

Cf. variant: A055830, A122075, A122950, A208337.
Cf. A167704 (diagonal sums), A000079 (row sums).
Cf. A111006.

Programs

  • Haskell
    a236076 n k = a236076_tabl !! n !! k
    a236076_row n = a236076_tabl !! n
    a236076_tabl = [1] : [0, 2] : f [1] [0, 2] where
       f us vs = ws : f vs ws where
         ws = [0] ++ zipWith (+) (zipWith (+) ([0] ++ us) (us ++ [0])) vs
    -- Reinhard Zumkeller, Jan 19 2014
    
  • Mathematica
    T[n_, k_]:= If[k<0 || k>n, 0, If[n==0 && k==0, 1, If[k==0, 0, If[n==1 && k==1, 2, T[n-1, k-1] + T[n-2, k-1] + T[n-2, k-2]]]]]; Table[T[n,k], {n,0,10}, {k,0,n}]//Flatten (* G. C. Greubel, May 21 2019 *)
  • PARI
    {T(n,k) = if(k<0 || k>n, 0, if(n==0 && k==0, 1, if(k==0, 0, if(n==1 && k==1, 2, T(n-1,k-1) + T(n-2,k-1) + T(n-2,k-2) ))))}; \\ G. C. Greubel, May 21 2019
    
  • Sage
    def T(n, k):
        if (k<0 or k>n): return 0
        elif (n==0 and k==0): return 1
        elif (k==0): return 0
        elif (n==1 and k==1): return 2
        else: return T(n-1,k-1) + T(n-2,k-1) + T(n-2,k-2)
    [[T(n, k) for k in (0..n)] for n in (0..10)] # G. C. Greubel, May 21 2019

Formula

G.f.: (1+x*y)/(1 - x*y - x^2*y - x^2*y^2).
T(n,k) = T(n-1,k-1) + T(n-2,k-1) + T(n-2,k-2), T(0,0)=1, T(1,0) = 0, T(1,1) = 2, T(n,k) = 0 if k < 0 or if k > n.
Sum_{k=0..n} T(n,k) = 2^n = A000079(n).
Sum_{n>=k} T(n,k) = A078057(k) = A001333(k+1).
T(n,n) = Fibonacci(n+2) = A000045(n+2).
T(n+1,n) = A023610(n-1), n >= 1.
T(n+2,n) = A129707(n).
Previous Showing 11-14 of 14 results.