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.

A108084 Triangle, read by rows, where T(0,0) = 1, T(n,k) = 2^n*T(n-1,k) + T(n-1,k-1).

Original entry on oeis.org

1, 2, 1, 8, 6, 1, 64, 56, 14, 1, 1024, 960, 280, 30, 1, 32768, 31744, 9920, 1240, 62, 1, 2097152, 2064384, 666624, 89280, 5208, 126, 1, 268435456, 266338304, 87392256, 12094464, 755904, 21336, 254, 1, 68719476736, 68451041280, 22638755840, 3183575040, 205605888, 6217920, 86360, 510, 1
Offset: 0

Views

Author

Gerald McGarvey, Jun 05 2005

Keywords

Comments

Triangle T(n,k), 0 <= k <= n, read by rows given by [2, 2, 8, 12, 32, 56, 128, 240, 512, ...] DELTA [1, 0, 2, 0, 4, 0, 8, 0, 16, 0, 32, 0, ...] = A014236 (first zero omitted) DELTA A077957 where DELTA is the operator defined in A084938. - Philippe Deléham, Aug 23 2006

Examples

			Triangle begins:
      1;
      2,     1;
      8,     6,    1;
     64,    56,   14,    1;
   1024,   960,  280,   30,  1;
  32768, 31744, 9920, 1240, 62, 1;
		

Crossrefs

Cf. A023531 (q=0), A007318 (q=1), this sequence (q=2), A173007 (q=3), A173008 (q=4).

Programs

  • Magma
    function T(n,k,q)
      if k lt 0 or k gt n then return 0;
      elif k eq n then return 1;
      else return q^n*T(n-1,k,q) + T(n-1,k-1,q);
      end if; return T; end function;
    [T(n,k,2): k in [0..n], n in [0..10]]; // G. C. Greubel, Feb 20 2021
  • Mathematica
    T[n_, k_, q_]:= T[n,k,q]= If[k<0 || k>n, 0, If[k==n, 1, q^n*T[n-1,k,q] +T[n-1,k-1,q] ]];
    Table[T[n,k,2], {n,0,10}, {k,0,n}]//Flatten (* G. C. Greubel, Feb 20 2021 *)
  • Sage
    def T(n, k, q):
        if (k<0 or k>n): return 0
        elif (k==n): return 1
        else: return q^n*T(n-1,k,q) + T(n-1,k-1,q)
    flatten([[T(n,k,2) for k in (0..n)] for n in (0..10)]) # G. C. Greubel, Feb 20 2021
    

Formula

Sum_{k=0..n} T(n, k) = A028362(n).
T(n,0) = 2^(n*(n+1)/2) = A006125(n+1). - Philippe Deléham, Nov 05 2006
T(n,k) = 2^binomial(n+1-k,2) * A022166(n,k) for 0 <= k <= n. - Werner Schulte, Mar 25 2019

A108085 Triangle, read by rows, where T(0,0) = 1, T(n,k) = 2^n*T(n-1,k) - T(n-1,k-1).

Original entry on oeis.org

1, 2, -1, 8, -6, 1, 64, -56, 14, -1, 1024, -960, 280, -30, 1, 32768, -31744, 9920, -1240, 62, -1, 2097152, -2064384, 666624, -89280, 5208, -126, 1, 268435456, -266338304, 87392256, -12094464, 755904, -21336, 254, -1, 68719476736, -68451041280, 22638755840, -3183575040, 205605888, -6217920
Offset: 0

Views

Author

Gerald McGarvey, Jun 05 2005

Keywords

Comments

For n > 0, n-th row sum = Product_{i=1..n} (2^i - 1), i.e., A005329(n).
Triangle T(n,k), 0 <= k <= n, read by rows given by [2, 2, 8, 12, 32, 56, 128, 240, 512, ...] DELTA [-1, 0, -2, 0, -4, 0, -8, 0, -16, 0, -32, 0, ...] = A014236(first zero omitted)DELTA -A077957 where DELTA is the operator defined in A084938. - Philippe Deléham, Aug 23 2006

Examples

			Triangle begins
     1;
     2,   -1;
     8,   -6,   1;
    64,  -56,  14,  -1;
  1024, -960, 280, -30, 1;
		

Programs

  • PARI
    t(n, k) = {if (k < 0, return (0)); if (n < k, return (0)); if (n == 0, return (1)); return (2^n*t(n-1,k) - t(n-1,k-1));}  \\ Michel Marcus, Apr 11 2013
Showing 1-2 of 2 results.