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.

A330140 Triangle read by rows: binomial transform of a signed variant of triangle A026300 with alternating signs in each column.

Original entry on oeis.org

1, 0, 1, 0, 0, 2, 0, 0, 1, 4, 0, 0, 1, 4, 9, 0, 0, 1, 5, 15, 21, 0, 0, 1, 6, 24, 50, 51, 0, 0, 1, 7, 35, 98, 161, 127, 0, 0, 1, 8, 48, 168, 378, 504, 323, 0, 0, 1, 9, 63, 264, 750, 1386, 1554, 835, 0, 0, 1, 10, 80, 390, 1335, 3132, 4920, 4740, 2188
Offset: 0

Views

Author

Gary W. Adamson, Dec 02 2019

Keywords

Examples

			The signed variant of triangle A026300 begins:
   1;
  -1,   1;
   1,  -2,   2;
  -1,   3,  -5,   4;
   1,  -4,   9, -12,   9;
  ...
The binomial transform of the foregoing is as shown below.
Written as a triangle the sequence begins:
  1;
  0,  1;
  0,  0,  2;
  0,  0,  1,  4;
  0,  0,  1,  4,  9;
  0,  0,  1,  5, 15, 21;
  0,  0,  1,  6, 24, 50, 51;
  ...
		

Crossrefs

Right border gives A001006, the Motzkin numbers.
Row sums give A000108, the Catalan numbers.

Programs

  • Magma
    F:= func< n,k | (-1)^(n+k)*&+[Binomial(n,2*i+n-k)*(Binomial(2*i+n-k,i) - Binomial(2*i+n-k,i-1)): i in [0..Floor(k/2)]] >;
    T:= func< n,k | &+[Binomial(n,j)*F(j,k): j in [k..n]] >;
    [T(n,k): k in [0..n], n in [0..10]]; // G. C. Greubel, Jan 06 2020
  • Mathematica
    F[n_, k_]:= (-1)^(n+k)*Sum[Binomial[n, 2i+n-k]*(Binomial[2i+n-k, i] - Binomial[2i+n-k, i-1]), {i,0,Floor[k/2]}]; T[n_, k_]:= Sum[Binomial[n, j]*F[j, k], {j,k,n}]; Table[T[n, k], {n,0,10}, {k,0,n}]//Flatten (* G. C. Greubel, Jan 06 2020 *)