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.

A136555 Square array, read by antidiagonals, where T(n,k) = binomial(2^k + n-1, k).

Original entry on oeis.org

1, 1, 1, 1, 2, 3, 1, 3, 6, 35, 1, 4, 10, 56, 1365, 1, 5, 15, 84, 1820, 169911, 1, 6, 21, 120, 2380, 201376, 67945521, 1, 7, 28, 165, 3060, 237336, 74974368, 89356415775, 1, 8, 36, 220, 3876, 278256, 82598880, 94525795200, 396861704798625, 1, 9, 45, 286, 4845, 324632, 90858768, 99949406400, 409663695276000, 6098989894499557055
Offset: 0

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Author

Paul D. Hanna, Jan 07 2008

Keywords

Comments

Let vector R_{n} equal row n of this array; then R_{n+1} = P * R_{n} for n>=0, where triangle P = A132625 such that row n+1 of P = row n of P^(2^n) with appended '1' for n>=0.

Examples

			Square array begins:
  1, 1,  3,  35, 1365, 169911,  67945521,  89356415775, ... A136556;
  1, 2,  6,  56, 1820, 201376,  74974368,  94525795200, ... A014070;
  1, 3, 10,  84, 2380, 237336,  82598880,  99949406400, ... A136505;
  1, 4, 15, 120, 3060, 278256,  90858768, 105637584000, ... A136506;
  1, 5, 21, 165, 3876, 324632,  99795696, 111600996000, ... ;
  1, 6, 28, 220, 4845, 376992, 109453344, 117850651776, ... ;
  1, 7, 36, 286, 5985, 435897, 119877472, 124397910208, ... ;
  1, 8, 45, 364, 7315, 501942, 131115985, 131254487936, ... ;
  ...
Form column vector R_{n} out of row n of this array;
then row n+1 can be generated from row n by:
R_{n+1} = P * R_{n} for n>=0,
where triangular matrix P = A132625 begins:
        1;
        1,      1;
        2,      1,     1;
       14,      4,     1,    1;
      336,     60,     8,    1,  1;
    25836,   2960,   248,   16,  1, 1;
  6251504, 454072, 24800, 1008, 32, 1, 1; ...
where row n+1 of P = row n of P^(2^n) with appended '1' for n>=0.
		

Crossrefs

Diagonals: A060690, A132683, A132684.
Cf. A136557 (antidiagonal sums).
Cf. A132625.

Programs

  • Magma
    [Binomial(2^k +n-k-1, k): k in [0..n], n in [0..12]]; // G. C. Greubel, Mar 14 2021
  • Maple
    A136555:= (n,k) -> binomial(2^k +n-k-1, k); seq(seq(A136555(n,k), k=0..n), n=0..12); # G. C. Greubel, Mar 14 2021
  • Mathematica
    Table[Binomial[2^k +n-k-1, k], {n,0,12}, {k,0,n}]//Flatten (* G. C. Greubel, Mar 14 2021 *)
  • PARI
    T(n,k)=binomial(2^k+n-1,k)
    
  • PARI
    /* Coefficient of x^k in g.f. of row n: */ T(n,k)=polcoeff(sum(i=0,k,(1+2^i*x+x*O(x^k))^(n-1)*log((1+2^i*x)+x*O(x^k))^i/i!),k)
    
  • Sage
    flatten([[binomial(2^k +n-k-1, k) for k in (0..n)] for n in (0..12)]) # G. C. Greubel, Mar 14 2021
    

Formula

G.f. for row n: Sum_{i>=0} (1 + 2^i*x)^(n-1) * log(1 + 2^i*x)^i / i!.
From G. C. Greubel, Mar 14 2021: (Start)
For the square array:
T(n, n) = A060690(n).
T(n+1, n) = A132683(n), T(n+2, n) = A132684(n).
T(2*n+1, n) = A132685(n), T(2*n, n) = A132686(n).
T(3*n+2, n) = A132689(n), T(3*n+1, n) = A132688(n), T(3*n, n) = A132687(n).
For the number triangle:
t(n, k) = T(n-k, k) = binomial(2^k + n - k -1, k).
Sum_{k=0..n} t(n,k) = Sum_{k=0..n} T(n-k, k) = A136557(n). (End)