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.

A258310 T(n,k) = 1/k! * Sum_{i=0..k} (-1)^(k-i) *C(k,i) * A258309(n,i); triangle T(n,k), n>=0, 0<=k<=floor(n/2), read by rows.

Original entry on oeis.org

1, 1, 2, 1, 4, 3, 9, 14, 3, 21, 50, 15, 51, 204, 122, 15, 127, 784, 644, 105, 323, 3212, 4115, 1310, 105, 835, 13068, 22587, 9270, 945, 2188, 55475, 137503, 85109, 16764, 945, 5798, 238073, 787127, 614779, 149754, 10395
Offset: 0

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Author

Alois P. Heinz, May 25 2015

Keywords

Examples

			Triangle T(n,k) begins:
:    1;
:    1;
:    2,     1;
:    4,     3;
:    9,    14,      3;
:   21,    50,     15;
:   51,   204,    122,    15;
:  127,   784,    644,   105;
:  323,  3212,   4115,  1310,   105;
:  835, 13068,  22587,  9270,   945;
: 2188, 55475, 137503, 85109, 16764, 945;
		

Crossrefs

Column k=0 gives A001006.
T(2n,n) gives A001147.
Row sums give A258311.

Programs

  • Maple
    b:= proc(x, y, t, k) option remember; `if`(y>x or y<0, 0,
          `if`(x=0, 1, b(x-1, y-1, false, k)*`if`(t, (k*x+y)/y, 1)
                      +b(x-1, y, false, k) +b(x-1, y+1, true, k)))
        end:
    A:= (n, k)-> b(n, 0, false, k):
    T:= proc(n, k) option remember;
           add(A(n, i)*(-1)^(k-i)*binomial(k, i), i=0..k)/k!
        end:
    seq(seq(T(n, k), k=0..n/2), n=0..14);
  • Mathematica
    b[x_, y_, t_, k_] := b[x, y, t, k] = If[y > x || y < 0, 0,
         If[x == 0, 1, b[x - 1, y - 1, False, k]*If[t, (k*x + y)/y, 1]
                     + b[x - 1, y, False, k] + b[x - 1, y + 1, True, k]]];
    A[n_, k_] := b[n, 0, False, k];
    T[n_, k_] := Sum[A[n, i] (-1)^(k - i) Binomial[k, i], {i, 0, k}]/k!;
    Table[Table[T[n, k], {k, 0, n/2}], {n, 0, 14}] // Flatten (* Jean-François Alcover, May 01 2022, after Alois P. Heinz *)