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.

A173007 Triangle T(n,k) read by rows: coefficient [x^k] of the polynomial Product_{i=1..n} (x + q^i) in row n and q = 3.

Original entry on oeis.org

1, 3, 1, 27, 12, 1, 729, 351, 39, 1, 59049, 29160, 3510, 120, 1, 14348907, 7144929, 882090, 32670, 363, 1, 10460353203, 5223002148, 650188539, 24698520, 297297, 1092, 1, 22876792454961, 11433166050879, 1427185336941, 54665851779, 674887059, 2685501, 3279, 1
Offset: 0

Views

Author

Roger L. Bagula, Feb 07 2010

Keywords

Comments

Triangle T(n,k), read by rows, given by [3,6,27,72,243,702,2187,6480,...] DELTA [1,0,3,0,9,0,27,0,81,0,243,0,...] where DELTA is the operator defined in A084938. - Philippe Deléham, Oct 01 2011

Examples

			Triangle begins as:
            1;
            3,          1;
           27,         12,         1;
          729,        351,        39,        1;
        59049,      29160,      3510,      120,      1;
     14348907,    7144929,    882090,    32670,    363,    1;
  10460353203, 5223002148, 650188539, 24698520, 297297, 1092, 1;
		

Crossrefs

Cf. A023531 (q=0), A007318 (q=1), A108084 (q=2), this sequence (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,3): k in [0..n], n in [0..10]]; // G. C. Greubel, Feb 20 2021
  • Mathematica
    (* First program *)
    p[x_, n_, q_] = If[n==0, 1, Product[x + q^i, {i, 1, n}]];
    Table[CoefficientList[p[x, n, 3], x], {n, 0, 10}] (* 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,3], {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,3) for k in (0..n)] for n in (0..10)]) # G. C. Greubel, Feb 20 2021
    

Formula

p(x,n,q) = 1 if n=0, Product_{i=1..n} (x + q^i) otherwise, with q=3.
T(n,k) = 3^n*T(n-1,k) + T(n-1,k-1), T(0,0)=1. - Philippe Deléham, Oct 01 2011
Sum_{k=0..n} T(n, k, 4) = A290000(n+1). - G. C. Greubel, Feb 20 2021

Extensions

Edited by G. C. Greubel, Feb 20 2021

A203229 (n-1)-st elementary symmetric function of (1,16,...,n^4).

Original entry on oeis.org

1, 17, 1393, 357904, 224021776, 290539581696, 697854274212096, 2859056348455305216, 18760911610508623282176, 187626456226399005573120000, 2747212346823835568109649920000, 56968733990900457398848318341120000
Offset: 1

Views

Author

Clark Kimberling, Dec 30 2011

Keywords

Crossrefs

Column k=4 of A291556.

Programs

  • Mathematica
    f[k_] := k^4; t[n_] := Table[f[k], {k, 1, n}]
    a[n_] := SymmetricPolynomial[n - 1, t[n]]
    Table[a[n], {n, 1, 14}]     (* A203229 *)
    Table[(n!)^4 * Sum[1/i^4, {i, 1, n}], {n, 1, 20}] (* Vaclav Kotesovec, Aug 27 2017 *)

Formula

a(n) ~ 2 * Pi^6 * n^(4*n+2) / (45*exp(4*n)). - Vaclav Kotesovec, Aug 27 2017
Sum_{n>=1} a(n) * x^n / (n!)^4 = polylog(4,x) / (1 - x). - Ilya Gutkovskiy, Jul 14 2020

A203149 (n-1)-st elementary symmetric function of {2,8,26,80,242,...,-1+3^n}.

Original entry on oeis.org

1, 10, 276, 22496, 5477312, 3995536896, 8740106791936, 57347917373194240, 1128805788065906196480, 66655379003341682687344640, 11807831483305724934163060490240, 6275171273199511284527725270165094400, 10004652813703079731923092657993740504268800
Offset: 1

Views

Author

Clark Kimberling, Dec 29 2011

Keywords

Crossrefs

Cf. A203148.

Programs

  • Mathematica
    f[k_] := 3^k - 1; t[n_] := Table[f[k], {k, 1, n}]
    a[n_] := SymmetricPolynomial[n - 1, t[n]]
    Table[a[n], {n, 1, 16}] (* A203149 *)
Showing 1-3 of 3 results.