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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.

A028324 Elements to the right of the central elements of the 5-Pascal triangle A028313 that are not 1.

Original entry on oeis.org

6, 7, 19, 8, 27, 9, 65, 36, 10, 101, 46, 11, 231, 147, 57, 12, 378, 204, 69, 13, 840, 582, 273, 82, 14, 1422, 855, 355, 96, 15, 3102, 2277, 1210, 451, 111, 16, 5379, 3487, 1661, 562, 127, 17, 11583, 8866, 5148, 2223, 689, 144, 18, 20449, 14014, 7371, 2912, 833
Offset: 0

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			This sequence represents the following portion of A028313(n,k), with x being the elements of A028313(2*n,n):
  x;
  .,  .;
  .,  x,  .;
  .,  .,  6,   .;
  .,  .,  x,   7,   .;
  .,  .,  .,  19,   8,   .;
  .,  .,  .,   x,  27,   9,   .;
  .,  .,  .,   .,  65,  36,  10,   .;
  .,  .,  .,   .,   x, 101,  46,  11,  .;
  .,  .,  .,   .,   ., 231, 147,  57, 12,  .;
  .,  .,  .,   .,   .,   x, 378, 204, 69, 13,  .;
As an irregular triangle this sequence begins as:
      6;
      7;
     19,    8;
     27,    9;
     65,   36,   10;
    101,   46,   11;
    231,  147,   57,   12;
    378,  204,   69,   13;
    840,  582,  273,   82,  14;
   1422,  855,  355,   96,  15;
   3102, 2277, 1210,  451, 111,  16;
   5379, 3487, 1661,  562, 127,  17;
  11583, 8866, 5148, 2223, 689, 144, 18;
		

Crossrefs

Programs

  • Magma
    A028324:= func< n,k | Binomial(n+3, k+2+Floor((n+1)/2)) + 3*Binomial(n+1, k+1+Floor((n+1)/2)) >;
    [A028324(n,k): k in [0..Floor(n/2)], n in [0..16]]; // G. C. Greubel, Jan 06 2024
    
  • Mathematica
    T[n_, k_]:= Binomial[n+3, k+2+Floor[(n+1)/2]] + 3*Binomial[n+1, k+1 + Floor[(n+1)/2]];
    Table[T[n,k], {n,0,16}, {k,0,Floor[n/2]}]//Flatten (* G. C. Greubel, Jan 06 2024 *)
  • SageMath
    def A028324(n,k): return binomial(n+3, k+2+(n+1)//2) + 3*binomial(n+1, k+1+((n+1)//2))
    flatten([[A028324(n,k) for k in range(1+(n//2))] for n in range(17)]) # G. C. Greubel, Jan 06 2024

Formula

T(n, k) = binomial(n+3, k + 2 + floor((n+1)/2)) + 3*binomial(n+1, k + 1 + floor((n+1)/2)), for 0 <= k <= floor(n/2), n >= 0. - G. C. Greubel, Jan 06 2024

Extensions

More terms from James Sellers