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.

Showing 1-2 of 2 results.

A193791 Mirror of the triangle A193790.

Original entry on oeis.org

1, 1, 1, 3, 2, 1, 9, 4, 4, 1, 27, 8, 12, 6, 1, 81, 16, 32, 24, 8, 1, 243, 32, 80, 80, 40, 10, 1, 729, 64, 192, 240, 160, 60, 12, 1, 2187, 128, 448, 672, 560, 280, 84, 14, 1, 6561, 256, 1024, 1792, 1792, 1120, 448, 112, 16, 1, 19683, 512, 2304, 4608, 5376, 4032
Offset: 0

Views

Author

Clark Kimberling, Aug 05 2011

Keywords

Comments

A193791 is obtained by reversing the rows of the triangle A193790.

Examples

			First six rows:
1
1....1
3....2....1
9....4....4....1
27..8....12....6...1
81...16...32....24...8....1
		

Crossrefs

Cf. A193790.

Programs

  • Mathematica
    z = 10; a = 2; b = 1;
    p[n_, x_] := (a*x + b)^n
    q[n_, x_] := 1 + x^n ; q[n_, 0] := q[n, x] /. x -> 0;
    t[n_, k_] := Coefficient[p[n, x], x^k]; t[n_, 0] := p[n, x] /. x -> 0;
    w[n_, x_] := Sum[t[n, k]*q[n + 1 - k, x], {k, 0, n}]; w[-1, x_] := 1
    g[n_] := CoefficientList[w[n, x], {x}]
    TableForm[Table[Reverse[g[n]], {n, -1, z}]]
    Flatten[Table[Reverse[g[n]], {n, -1, z}]]  (* A193790 *)
    TableForm[Table[g[n], {n, -1, z}]]
    Flatten[Table[g[n], {n, -1, z}]]  (* A193791 *)

Formula

Write w(n,k) for the triangle at A193790. The triangle at A193791 is then given by w(n,n-k).

A182059 Triangle, read by rows, given by (0, 2, -1/2, 1/2, 0, 0, 0, 0, 0, 0, 0, ...) DELTA (2, 0, -1, 1, 0, 0, 0, 0, 0, 0, 0, ...) where DELTA is the operator defined in A084938.

Original entry on oeis.org

1, 0, 2, 0, 4, 4, 0, 6, 12, 8, 0, 8, 24, 32, 16, 0, 10, 40, 80, 80, 32, 0, 12, 60, 160, 240, 192, 64, 0, 14, 84, 280, 560, 672, 448, 128, 0, 16, 112, 448, 1120, 1792, 1792, 1024, 256, 0, 18, 144, 672, 2016, 4032, 5376, 4608, 2304, 512
Offset: 0

Views

Author

Philippe Deléham, Apr 09 2012

Keywords

Comments

Row sums are 3^n - 1 + 0^n.
Triangle of coefficients in expansion of (1+2*x)^n - 1 + 0^n .

Examples

			Triangle begins :
1
0, 2
0, 4, 4
0, 6, 12, 8
0, 8, 24, 32, 16
0, 10, 40, 80, 80, 32
0, 12, 60, 160, 240, 192, 64
0, 14, 84, 280, 560, 672, 448, 128
0, 16, 112, 448, 1120, 1792, 1792, 1024, 256
0, 18, 144, 672, 2016, 4032, 5376, 4608, 2304, 512
0, 20, 180, 960, 3360, 8064, 13440, 15360, 11520, 5120, 1024
		

Crossrefs

Formula

G.f.: (1-2*x+x^2+2*y*x^2)/(1-2*x-2*y*x+x^2+2*y*x^2).
T(n,k) = 2*T(n-1,k) + 2*T(n-1,k-1) - T(n-2,k) - 2*T(n-2,k-1), T(0,0) = 1, T(1,0) = T(2,0) = 0, T(1,1) = 2, T(2,1) = T(2,2) = 4 and T(n,k) = 0 if k<0 or if k>n.
T(n,k) = A206735(n,k)*2^k.
T(n,k) = A013609(n,k) - A073424(n,k) .
Showing 1-2 of 2 results.