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.

A022171 Triangle of Gaussian binomial coefficients [ n,k ] for q = 7.

Original entry on oeis.org

1, 1, 1, 1, 8, 1, 1, 57, 57, 1, 1, 400, 2850, 400, 1, 1, 2801, 140050, 140050, 2801, 1, 1, 19608, 6865251, 48177200, 6865251, 19608, 1, 1, 137257, 336416907, 16531644851, 16531644851, 336416907, 137257, 1, 1
Offset: 0

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Examples

			Triangle begins:
  1;
  1,      1;
  1,      8,         1;
  1,     57,        57,           1;
  1,    400,      2850,         400,           1;
  1,   2801,    140050,      140050,        2801,         1;
  1,  19608,   6865251,    48177200,     6865251,     19608,      1;
  1, 137257, 336416907, 16531644851, 16531644851, 336416907, 137257, 1;
		

References

  • F. J. MacWilliams and N. J. A. Sloane, The Theory of Error-Correcting Codes, Elsevier-North Holland, 1978, p. 698.

Crossrefs

Cf. A023000 (k=1), A022231 (k=2)

Programs

  • Maple
    A027875 := proc(n)
        mul(7^i-1,i=1..n) ;
    end proc:
    A022171 := proc(n,m)
        A027875(n)/A027875(m)/A027875(n-m) ;
    end proc: # R. J. Mathar, Jul 19 2017
  • Mathematica
    p[n_]:=Product[7^i - 1, {i, 1, n}]; t[n_, k_]:=p[n]/(p[k]*p[n - k]); Table[t[n, k], {n, 0, 15}, {k, 0, n}]//Flatten (* Vincenzo Librandi, Aug 13 2016 *)
    Table[QBinomial[n,k,7], {n,0,10}, {k,0,n}]//Flatten (* or *) q:= 7; T[n_, 0]:= 1; T[n_,n_]:= 1; T[n_,k_]:= T[n,k] = If[k < 0 || n < k, 0, T[n-1, k -1] +q^k*T[n-1,k]]; Table[T[n,k], {n,0,10}, {k,0,n}] // Flatten  (* G. C. Greubel, May 27 2018 *)
  • PARI
    {q=7; T(n,k) = if(k==0,1, if (k==n, 1, if (k<0 || nG. C. Greubel, May 27 2018

Formula

T(n,k) = T(n-1,k-1) + q^k * T(n-1,k). - Peter A. Lawrence, Jul 13 2017
G.f. of column k: x^k * exp( Sum_{j>=1} f((k+1)*j)/f(j) * x^j/j ), where f(j) = 7^j - 1. - Seiichi Manyama, May 09 2025