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.

A308737 Triangle of scaled 1-tiered binomial coefficients, T(n,k) = 2^(n+1)*(n-k,k)_1 (n >= 0, 0 <= k <= n), where (N,M)_1 is the 1-tiered binomial coefficient.

Original entry on oeis.org

1, 1, 3, 1, 8, 7, 1, 17, 31, 15, 1, 34, 96, 94, 31, 1, 67, 258, 382, 253, 63, 1, 132, 645, 1280, 1275, 636, 127, 1, 261, 1545, 3845, 5115, 3831, 1531, 255, 1, 518, 3598, 10766, 17920, 17906, 10738, 3578, 511, 1, 1031, 8212, 28700, 57358, 71666, 57316, 28652, 8185, 1023
Offset: 0

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Author

Michel Marcus, Jun 21 2019

Keywords

Examples

			From _Petros Hadjicostas_, Jul 07 2020: (Start)
Square array for (N,M)_1 of 1-tiered binomial coefficients (N, M >= 0):
  1/2,   3/4,    7/8,     15/16,   31/32,     63/64,   127/128, ...
  1/4,    1,    31/16,    47/16,  253/64,    159/32,  1531/256, ...
  1/8,  17/16,    3,     191/32, 1275/128,  3831/256,  5369/256, ...
  1/16, 17/16, 129/32,     10,   5115/256,  8953/256, 14329/256, ...
  1/32, 67/64, 645/128, 3845/256,   35,    35833/512, 129003/1024, ...
  ... (End)
Triangle (n-k,k)_1 of 1-tiered binomial coefficients (n >= 0 and k = 0..n):
  1/2,
  1/4,    3/4,
  1/8,     1,    7/8,
  1/16,  17/16, 31/16, 15/16,
  1/32,  17/16,   3,   47/16, 31/32,
  ...
Scaled triangle T(n,k) after multiplying each row by 2^(n+1):
  1,
  1,  3,
  1,  8,  7,
  1, 17, 31, 15,
  1, 34, 96, 94, 31,
  ...
		

Crossrefs

Cf. A007318 (Pascal triangle: 0-tiered binomial coefficient), A038208, A145071 (column k = 1).

Programs

  • Mathematica
    rows = 10;
    cc = CoefficientList[# + O[y]^rows, y]& /@ CoefficientList[(1-x)/((1-x-y)* (2-x-y)) + O[x]^rows, x];
    T[n_, m_, 1] := cc[[n-m+1, m+1]];
    Table[2^(n+1) Table[T[n, m, 1], {m, 0, n}], {n, 0, rows-1}] (* Jean-François Alcover, Jun 21 2019 *)
  • PARI
    T(n,m) = if ((n==0) && (m==0), 1/2, binomial(n+m-1, m-1) - (binomial(n+m,n)/2 - binomial(n+m-1,n-1))/2^(n+m));
    TT(n, k) = T(n-k, k);
    tabls(nn) = for (n=0, nn, for (k=0, n, print1(2^(n+1)*TT(n, k), ", ")));

Formula

Scaled coefficients satisfy T(n,0) = 1 for n >= 0 and T(n,k) = T(n-1,k) + T(n-1,k-1) + 2^n*C(n-1,k-1) for n >= k+1 >= 1. - Charlie Neder, Jun 21 2019 [Corrected by Petros Hadjicostas, Jul 06 2020]
From Petros Hadjicostas, Jul 07 2020: (Start)
(N,M)_1 + (M,N)_1 = (N,M)_0 = binomial(N+M, N) for N, M >= 0.
(n-k,k)_1 + (k, n-k)_1 = binomial(n,k) for n >= k >= 0.
T(n,k) + T(n,n-k) = 2^(n+1)*binomial(n,k) = 2*A038208(n,k) for n >= k >= 0.
T(n,k) = 2^(n + 1)*binomial(n-1, k-1) + 2*binomial(n-1,k) - binomial(n,k) for n >= k >= 0 and (n,k) <> (0,0) with T(0,0) = 1.
G.f. for T(n,k): (1 - 2*x)/((1 - 2*x*(1 + y))*(1 - x*(1 + y))). (End)

Extensions

Name edited by Petros Hadjicostas, Jul 07 2020