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.

Previous Showing 21-22 of 22 results.

A157277 Triangle T(n, k, m) = (m*(n-k) + 1)*T(n-1, k-1, m) + (m*k + 1)*T(n-1, k, m) + m*f(n,k)*T(n-2, k-1, m) with T(n, 0, m) = T(n, n, m) = 1, f(n, k) = 2*k if k <= floor(n/2) otherwise 2*(n-k), and m = 2, read by rows.

Original entry on oeis.org

1, 1, 1, 1, 10, 1, 1, 39, 39, 1, 1, 128, 470, 128, 1, 1, 397, 3558, 3558, 397, 1, 1, 1206, 22387, 55452, 22387, 1206, 1, 1, 3635, 128377, 632343, 632343, 128377, 3635, 1, 1, 10924, 698788, 6107192, 12269406, 6107192, 698788, 10924, 1, 1, 32793, 3686880, 53375112, 187721254, 187721254, 53375112, 3686880, 32793, 1
Offset: 0

Views

Author

Roger L. Bagula, Feb 26 2009

Keywords

Examples

			Triangle begins as:
  1;
  1,     1;
  1,    10,      1;
  1,    39,     39,       1;
  1,   128,    470,     128,        1;
  1,   397,   3558,    3558,      397,       1;
  1,  1206,  22387,   55452,    22387,    1206,      1;
  1,  3635, 128377,  632343,   632343,  128377,   3635,     1;
  1, 10924, 698788, 6107192, 12269406, 6107192, 698788, 10924, 1;
		

Crossrefs

Programs

  • Mathematica
    f[n_,k_]:= If[k<=Floor[n/2], 2*k, 2*(n-k)];
    T[n_, k_, m_]:= T[n, k, m]= If[k==0 || k==n, 1, (m*(n-k)+1)*T[n-1,k-1,m] + (m*k+1)*T[n-1,k,m] + m*f[n,k]*T[n-2,k-1,m]];
    Table[T[n,k,2], {n,0,12}, {k,0,n}]//Flatten (* modified by G. C. Greubel, Feb 05 2022 *)
  • Sage
    def f(n,k): return 2*k if (k <= n//2) else 2*(n-k)
    @CachedFunction
    def T(n,k,m):  # A157277
        if (k==0 or k==n): return 1
        else: return (m*(n-k) +1)*T(n-1,k-1,m) + (m*k+1)*T(n-1,k,m) + m*f(n,k)*T(n-2,k-1,m)
    flatten([[T(n,k,2) for k in (0..n)] for n in (0..12)]) # G. C. Greubel, Feb 05 2022

Formula

T(n, k, m) = (m*(n-k) + 1)*T(n-1, k-1, m) + (m*k + 1)*T(n-1, k, m) + m*f(n,k)*T(n-2, k-1, m) with T(n, 0, m) = T(n, n, m) = 1, f(n, k) = 2*k if k <= floor(n/2) otherwise 2*(n-k), and m = 2.
T(n, n-k, m) = T(n, k, m).

Extensions

Edited by G. C. Greubel, Feb 05 2022

A157278 Triangle T(n, k, m) = (m*(n-k) + 1)*T(n-1, k-1, m) + (m*k + 1)*T(n-1, k, m) + m*f(n,k)*T(n-2, k-1, m) with T(n, 0, m) = T(n, n, m) = 1, f(n, k) = 2*k if k <= floor(n/2) otherwise 2*(n-k), and m = 3, read by rows.

Original entry on oeis.org

1, 1, 1, 1, 14, 1, 1, 69, 69, 1, 1, 292, 1134, 292, 1, 1, 1187, 11686, 11686, 1187, 1, 1, 4770, 100737, 254132, 100737, 4770, 1, 1, 19105, 795723, 4061249, 4061249, 795723, 19105, 1, 1, 76448, 5990296, 55157324, 111691642, 55157324, 5990296, 76448, 1
Offset: 0

Views

Author

Roger L. Bagula, Feb 26 2009

Keywords

Examples

			Triangle begins as:
  1;
  1,     1;
  1,    14,       1;
  1,    69,      69,        1;
  1,   292,    1134,      292,         1;
  1,  1187,   11686,    11686,      1187,        1;
  1,  4770,  100737,   254132,    100737,     4770,       1;
  1, 19105,  795723,  4061249,   4061249,   795723,   19105,     1;
  1, 76448, 5990296, 55157324, 111691642, 55157324, 5990296, 76448, 1;
		

Crossrefs

Programs

  • Mathematica
    f[n_,k_]:= If[k<=Floor[n/2], 2*k, 2*(n-k)];
    T[n_, k_, m_]:= T[n, k, m]= If[k==0 || k==n, 1, (m*(n-k)+1)*T[n-1,k-1,m] + (m*k+1)*T[n-1,k,m] + m*f[n,k]*T[n-2,k-1,m]];
    Table[T[n,k,3], {n,0,12}, {k,0,n}]//Flatten (* modified by G. C. Greubel, Feb 06 2022 *)
  • Sage
    def f(n,k): return 2*k if (k <= n//2) else 2*(n-k)
    @CachedFunction
    def T(n,k,m):  # A157278
        if (k==0 or k==n): return 1
        else: return (m*(n-k) +1)*T(n-1,k-1,m) + (m*k+1)*T(n-1,k,m) + m*f(n,k)*T(n-2,k-1,m)
    flatten([[T(n,k,3) for k in (0..n)] for n in (0..12)]) # G. C. Greubel, Feb 06 2022

Formula

T(n, k, m) = (m*(n-k) + 1)*T(n-1, k-1, m) + (m*k + 1)*T(n-1, k, m) + m*f(n,k)*T(n-2, k-1, m) with T(n, 0, m) = T(n, n, m) = 1, f(n, k) = 2*k if k <= floor(n/2) otherwise 2*(n-k), and m = 3.
T(n, n-k, m) = T(n, k, m).

Extensions

Edited by G. C. Greubel, Feb 06 2022
Previous Showing 21-22 of 22 results.