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 1-3 of 3 results.

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

A092897 Expansion of (1-x-x^2-3*x^3) / ((1+x)^2*(1-3*x)).

Original entry on oeis.org

1, 0, 4, 4, 24, 56, 188, 540, 1648, 4912, 14772, 44276, 132872, 398568, 1195756, 3587212, 10761696, 32285024, 96855140, 290565348, 871696120, 2615088280, 7845264924, 23535794684, 70607384144, 211822152336, 635466457108, 1906399371220, 5719198113768, 17157594341192
Offset: 0

Views

Author

Paul Barry, Mar 12 2004

Keywords

Comments

Binomial transform is A092896.

Crossrefs

Cf. A092896.

Programs

  • Magma
    [(3^n +4*0^n -(-1)^n*(1-4*n))/4: n in [0..30]]; // G. C. Greubel, Feb 20 2021
  • Mathematica
    LinearRecurrence[{1,5,3},{1,0,4,4},30] (* Harvey P. Dale, Mar 24 2018 *)
  • PARI
    Vec((1 - x - x^2 - 3*x^3) / ((1 + x)^2 * (1 - 3*x)) + O(x^30)) \\ Colin Barker, Nov 25 2016
    
  • Sage
    [(3^n +4*0^n -(-1)^n*(1-4*n))/4 for n in [0..30]]; # G. C. Greubel, Feb 20 2021
    

Formula

a(n) = (3^n + 4 * 0^n - (-1)^n + 4*n*(-1)^n)/4.
a(n) = a(n-1) + 5*a(n-2) + 3*a(n-3) for n>3. - Colin Barker, Nov 25 2016
E.g.f.: (4 +exp(3*x) -(1+4*x)*exp(-x))/4. - G. C. Greubel, Feb 20 2021

A092898 Expansion of (1 - 4*x + 4*x^2 - 4*x^3)/(1 - 4*x).

Original entry on oeis.org

1, 0, 4, 12, 48, 192, 768, 3072, 12288, 49152, 196608, 786432, 3145728, 12582912, 50331648, 201326592, 805306368, 3221225472, 12884901888, 51539607552, 206158430208, 824633720832, 3298534883328, 13194139533312, 52776558133248
Offset: 0

Views

Author

Paul Barry, Mar 12 2004

Keywords

Comments

Partial sums are A092896.

Crossrefs

Programs

  • Magma
    [1,0,4] cat [3*4^(n-2): n in [3..30]]; // G. C. Greubel, Feb 21 2021
  • Maple
    a:= n-> 3*4^n/16+13*0^n/16+add(binomial(n,k)*(-1)^k*(3*k/4+k*(k-1)/2), k=0..n):
    seq(a(n), n=0..30);  # Alois P. Heinz, Nov 03 2018
  • Mathematica
    Join[{1, 0, 4}, LinearRecurrence[{4}, {12}, 22]] (* Jean-François Alcover, Sep 16 2019 *)
  • PARI
    Vec((1 -4*x +4*x^2 -4*x^3)/(1-4*x) + O(x^30)) \\ Andrew Howroyd, Nov 03 2018
    
  • Sage
    [1,0,4]+[3*4^(n-2) for n in (3..30)] # G. C. Greubel, Feb 21 2021
    

Formula

a(n+2) = 4 * A002001(n).
a(n) = (3*4^n + 13*0^n)/16 + Sum_{k=0..n} binomial(n, k)*(-1)^k*(3*k/4 + k*(k-1)/2).
G.f.: 1 - x + 8*x^2 + 2*x/G(0), where G(k) = 1 + 1/(1 - x*(3*k+4)/(x*(3*k+7) + 1/G(k+1))); (continued fraction). - Sergei N. Gladkovskii, Jun 11 2013
a(n) = A110594(n-1) for n >= 2. - Georg Fischer, Nov 03 2018
From G. C. Greubel, Feb 21 2021: (Start)
a(n) = (3*4^n +16*[n=2] -12*[n=1] +13*0^n)/16.
E.g.f.: (13 -12*x + 8*x^2 + 3*exp(4*x))/16. (End)
Showing 1-3 of 3 results.