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 1-4 of 4 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

A173008 Triangle T(n,k) read by rows: coefficient [x^k] of the polynomial Product_{i=1..n} (x + q^i) in row n, column 0<=k<=n, and q = 4.

Original entry on oeis.org

1, 4, 1, 64, 20, 1, 4096, 1344, 84, 1, 1048576, 348160, 22848, 340, 1, 1073741824, 357564416, 23744512, 371008, 1364, 1, 4398046511104, 1465657589760, 97615085568, 1543393280, 5957952, 5460, 1, 72057594037927936, 24017731997138944, 1600791219535872, 25384570585088, 99158478848, 95414592, 21844, 1
Offset: 0

Views

Author

Roger L. Bagula, Feb 07 2010

Keywords

Comments

Row sums are 1, 5, 85, 5525, 1419925, 1455423125, 5962868543125, 97701601079103125, 6403069829921181503125, ... (partial products of A092896).
Triangle T(n,k), read by rows, given by [4,12,64,240,1024,4032,16384,...] DELTA [1,0,4,0,16,0,64,0,256,0,1024,0,...] where DELTA is the operator defined in A084938. - Philippe Deléham, Oct 01 2011

Examples

			Triangle begins as:
              1;
              4,             1;
             64,            20,           1;
           4096,          1344,          84,          1;
        1048576,        348160,       22848,        340,       1;
     1073741824,     357564416,    23744512,     371008,    1364,    1;
  4398046511104, 1465657589760, 97615085568, 1543393280, 5957952, 5460, 1;
		

Crossrefs

Cf. A023531 (q=0), A007318 (q=1), A108084 (q=2), A173007 (q=3), this sequence (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,4): k in [0..n], n in [0..10]]; // G. C. Greubel, Feb 20 2021
  • Maple
    P:= 1: A:= 1:
    for n from 1 to 12 do
      P:= expand(P*(x+4^n));
      A:= A, seq(coeff(P,x,j),j=0..n)
    od:
    A; # Robert Israel, Aug 12 2015
  • Mathematica
    (* First program *)
    p[x_, n_, q_]= If[n==0, 1, Product[x + q^i, {i,n}]];
    Table[CoefficientList[p[x, n, 4], x], {n, 0, 10}]//Flatten (* modified by G. C. Greubel, Feb 20 2021 *)
    (* Second program *)
    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,4], {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,4) for k in (0..n)] for n in (0..10)]) # G. C. Greubel, Feb 20 2021
    

Formula

T(n,k) = 4^n*T(n-1,k) + T(n-1,k-1) with T(0,0)=1. - Philippe Deléham, Oct 01 2011
Sum_{k=0..n} T(n, k, 4) = A309327(n+1). - G. C. Greubel, Feb 20 2021

A203148 (n-1)-st elementary symmetric function of {3,9,...,3^n}.

Original entry on oeis.org

1, 12, 351, 29160, 7144929, 5223002148, 11433166050879, 75035879252272080, 1477081305957768349761, 87223128348206814118735932, 15451489966710801620870785316511, 8211586182553137756809552940033725880, 13091937140529934508508023103481190655434529
Offset: 1

Views

Author

Clark Kimberling, Dec 29 2011

Keywords

Comments

From R. J. Mathar, Oct 01 2016: (Start)
The k-th elementary symmetric functions of the integers 3^j, j=1..n, form a triangle T(n,k), 0<=k<=n, n>=0:
1;
1 3;
1 12 27;
1 39 351 729;
1 120 3510 29160 59049;
1 363 32670 882090 7144929 14348907;
which is the row-reversed version of A173007. This here is the first subdiagonal. The diagonal seems to be A047656. The first column is A029858. (End)

Crossrefs

Programs

  • Magma
    [(1/2)*(3^n -1)*3^(Binomial(n,2)): n in [1..20]]; // G. C. Greubel, Feb 24 2021
  • Mathematica
    f[k_]:= 3^k; t[n_]:= Table[f[k], {k, 1, n}];
    a[n_]:= SymmetricPolynomial[n - 1, t[n]];
    Table[a[n], {n, 1, 16}] (* A203148 *)
    Table[1/2 (3^n - 1) 3^Binomial[n, 2], {n, 1, 20}] (* Emanuele Munarini, Sep 14 2017 *)
  • Sage
    [(1/2)*(3^n -1)*3^(binomial(n,2)) for n in (1..20)] # G. C. Greubel, Feb 24 2021
    

Formula

a(n) = (1/2)*(3^n-1)*3^(binomial(n,2)). - Emanuele Munarini, Sep 14 2017

A348014 Triangle, read by rows, with row n forming the coefficients in Product_{k=0..n} (1 + k^k*x).

Original entry on oeis.org

1, 1, 1, 1, 5, 4, 1, 32, 139, 108, 1, 288, 8331, 35692, 27648, 1, 3413, 908331, 26070067, 111565148, 86400000, 1, 50069, 160145259, 42405161203, 1216436611100, 5205269945088, 4031078400000
Offset: 0

Views

Author

Seiichi Manyama, Sep 24 2021

Keywords

Examples

			Triangle begins:
  1;
  1,    1;
  1,    5,      4;
  1,   32,    139,      108;
  1,  288,   8331,    35692,     27648;
  1, 3413, 908331, 26070067, 111565148, 86400000;
		

Crossrefs

Column k=1 gives A001923.
The diagonal of the triangle is A002109.

Programs

  • PARI
    T(n, k) = if(k==0, 1, if(k==n, prod(j=1, n, j^j), T(n-1, k)+n^n*T(n-1, k-1)));
    
  • PARI
    row(n) = Vecrev(prod(k=1, n, 1+k^k*x));

Formula

T(0,0) = 1; T(n,k) = T(n-1,k) + n^n * T(n-1,k-1).
Showing 1-4 of 4 results.