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.

A132752 Triangle T(n, k) = 2*A132749(n, k) - 1, read by rows.

Original entry on oeis.org

1, 3, 1, 3, 3, 1, 3, 5, 5, 1, 3, 7, 11, 7, 1, 3, 9, 19, 19, 9, 1, 3, 11, 29, 39, 29, 11, 1, 3, 13, 41, 69, 69, 41, 13, 1, 3, 15, 55, 111, 139, 111, 55, 15, 1, 3, 17, 71, 167, 251, 251, 167, 71, 17, 1
Offset: 0

Views

Author

Gary W. Adamson, Aug 28 2007

Keywords

Examples

			First few rows of the triangle are:
  1;
  3,  1;
  3,  3,  1;
  3,  5,  5,  1;
  3,  7, 11,  7,  1;
  3,  9, 19, 19,  9,  1;
  3, 11, 29, 39, 29, 11, 1;
  ...
		

Crossrefs

Programs

  • Magma
    A132752:= func< n,k | k eq n select 1 else k eq 0 select 3 else 2*Binomial(n,k) -1 >;
    [A132752(n,k): k in [0..n], n in [0..12]]; // G. C. Greubel, Feb 16 2021
  • Mathematica
    T[n_, k_]:= If[k==n, 1, If[k==0, 3, 2*Binomial[n, k] -1 ]];
    Table[T[n, k], {n,0,12}, {k,0,n}]//Flatten (* G. C. Greubel, Feb 16 2021 *)
  • Sage
    def A132752(n,k): return 1 if k==n else 3 if k==0 else 2*binomial(n,k) -1
    flatten([[A132752(n,k) for k in [0..n]] for n in [0..12]]) # G. C. Greubel, Feb 16 2021
    

Formula

T(n, k) = 2*A132749(n, k) - 1, an infinite lower triangular matrix.
From G. C. Greubel, Feb 16 2021: (Start)
T(n, k) = A109128(n, k) with T(n, 0) = 3.
Sum_{k=0..n} T(n, k) = 2^(n+1) -n +1 -2*[n=0] = A132753(n) - 2*[n=0]. (End)