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.

A174301 A symmetrical triangle: T(n,k) = binomial(n, k)*if(floor(n/2) greater than or equal to k then 4^k, otherwise 4^(n-k)).

Original entry on oeis.org

1, 1, 1, 1, 8, 1, 1, 12, 12, 1, 1, 16, 96, 16, 1, 1, 20, 160, 160, 20, 1, 1, 24, 240, 1280, 240, 24, 1, 1, 28, 336, 2240, 2240, 336, 28, 1, 1, 32, 448, 3584, 17920, 3584, 448, 32, 1, 1, 36, 576, 5376, 32256, 32256, 5376, 576, 36, 1, 1, 40, 720, 7680, 53760, 258048, 53760, 7680, 720, 40, 1
Offset: 0

Views

Author

Roger L. Bagula, Mar 15 2010

Keywords

Comments

Row sums are: {1, 2, 10, 26, 130, 362, 1810, 5210, 26050, 76490, ...}.

Examples

			Triangle begins:
  1;
  1,  1;
  1,  8,   1;
  1, 12,  12,    1;
  1, 16,  96,   16,     1;
  1, 20, 160,  160,    20,      1;
  1, 24, 240, 1280,   240,     24,     1;
  1, 28, 336, 2240,  2240,    336,    28,    1;
  1, 32, 448, 3584, 17920,   3584,   448,   32,   1;
  1, 36, 576, 5376, 32256,  32256,  5376,  576,  36,  1;
  1, 40, 720, 7680, 53760, 258048, 53760, 7680, 720, 40,  1;
		

Crossrefs

T(2n,n) gives A098430.

Programs

  • Magma
    [[Floor(n/2) ge k select 4^k*Binomial(n,k) else 4^(n-k)*Binomial(n,k): k in [0..n]]: n in [0..10]]; // G. C. Greubel, Apr 15 2019
    
  • Mathematica
    Table[Binomial[n, m]*If[Floor[n/2]>=m , 4^m, 4^(n-m)], {n,0,10}, {m,0,n} ]//Flatten
  • PARI
    {T(n,k) = binomial(n,k)*if(floor(n/2)>=k, 4^k, 4^(n-k))}; \\ G. C. Greubel, Apr 15 2019
    
  • Sage
    def T(n,k):
       if floor(n/2)>=k: return 4^k*binomial(n,k)
       else: return 4^(n-k)*binomial(n,k)
    [[T(n,k) for k in (0..n)] for n in (0..10)] # G. C. Greubel, Apr 15 2019

Formula

T(n, m) = binomial(n, m)*if(floor(n/2) greater than or equal to m then 4^m, otherwise 4^(n-m)).

Extensions

Edited by G. C. Greubel, Apr 15 2019

A174303 A symmetrical triangle: T(n,k) = A008292(n+1, k) * f(n,k), where f(n,k) = 2^k when floor(n/2) >= k, otherwise 2^(n-k).

Original entry on oeis.org

1, 1, 1, 1, 8, 1, 1, 22, 22, 1, 1, 52, 264, 52, 1, 1, 114, 1208, 1208, 114, 1, 1, 240, 4764, 19328, 4764, 240, 1, 1, 494, 17172, 124952, 124952, 17172, 494, 1, 1, 1004, 58432, 705872, 2499040, 705872, 58432, 1004, 1, 1, 2026, 191360, 3641536, 20965664, 20965664, 3641536, 191360, 2026, 1
Offset: 0

Views

Author

Roger L. Bagula, Mar 15 2010

Keywords

Comments

Row sums are: {1, 2, 10, 46, 370, 2646, 29338, 285238, 4029658, ...}.

Examples

			Triangle begins as:
  1;
  1,    1;
  1,    8,     1;
  1,   22,    22,      1;
  1,   52,   264,     52,       1;
  1,  114,  1208,   1208,     114,      1;
  1,  240,  4764,  19328,    4764,    240,     1;
  1,  494, 17172, 124952,  124952,  17172,   494,    1;
  1, 1004, 58432, 705872, 2499040, 705872, 58432, 1004,   1;
		

Crossrefs

Programs

  • Magma
    Eulerian:= func< n,k | (&+[(-1)^j*Binomial(n+1,j)*(k-j+1)^n: j in [0..k+1]]) >; [[Floor(n/2) ge k select 2^k*Eulerian(n+1,k) else 2^(n-k)*Eulerian(n+1,k): k in [0..n]]: n in [0..10]]; // G. C. Greubel, Apr 15 2019
    
  • Mathematica
    Eulerian[n_, k_]:= Sum[(-1)^j*Binomial[n+1,j]*(k-j+1)^n, {j,0,k+1}];
    Table[Eulerian[n+1,m]*If[Floor[n/2] >= m, 2^m, 2^(n-m)], {n,0,10}, {m,0,n} ]//Flatten (* modified by G. C. Greubel, Apr 15 2019 *)
  • PARI
    {eulerian(n,k) = sum(j=0,k+1, (-1)^j*binomial(n+1,j)*(k-j+1)^n)};
    for(n=0,10, for(k=0,n, print1(eulerian(n+1,k)*if(floor(n/2)>=k, 2^k, 2^(n-k)), ", "))) \\ G. C. Greubel, Apr 15 2019
    
  • Sage
    def Eulerian(n,k): return sum((-1)^j*binomial(n+1,j)*(k-j+1)^n for j in (0..k+1))
    def T(n,k):
       if floor(n/2)>=k: return 2^k*Eulerian(n+1,k)
       else: return 2^(n-k)*Eulerian(n+1,k)
    [[T(n,k) for k in (0..n)] for n in (0..10)] # G. C. Greubel, Apr 15 2019

Formula

T(n,k) = Eulerian(n+1, k)*if(floor(n/2) greater than or equal to k then 2^m otherwise 2^(n-k)), where the Eulerian numbers are defined as A008292(n,k).

Extensions

Edited by G. C. Greubel, Apr 15 2019
Showing 1-2 of 2 results.