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.

A203227 (n-1)-st elementary symmetric function of (0!,...,(n-1)!).

Original entry on oeis.org

1, 2, 5, 32, 780, 93888, 67633920, 340899840000, 13745206960128000, 4987865758275993600000, 18099969098565397826764800000, 722492853172221856076141690880000000, 346075232923849611911833538569175040000000000
Offset: 1

Views

Author

Clark Kimberling, Dec 30 2011

Keywords

Comments

Each term appears as an unreduced numerator in the following partial infinite sum: f(0) = 1; f(n) = f(n-1)/n; Sum_{k>=0}(f(k)) = e. - Daniel Suteu, Jul 30 2016
a(n)/A000178(n-1) -> e as n -> oo. - Daniel Suteu, Jul 30 2016

Examples

			For n=4, the 3rd elementary symmetric polynomial in the 4 variables a, b, c, and d is abc + abd + acd + bcd. Setting a = 0! = 1, b = 1! = 1, c = 2! = 2, and d = 3! = 6 gives a(4) = 1*1*2 + 1*1*6 + 1*2*6 + 1*2*6 = 2 + 6 + 12 + 12 = 32. - _Michael B. Porter_, Aug 17 2016
		

Crossrefs

Programs

  • Maple
    a:= n-> coeff(mul(i!*x+1, i=0..n-1), x, n-1):
    seq(a(n), n=1..15);  # Alois P. Heinz, Sep 08 2019
  • Mathematica
    f[k_] := (k - 1)!; t[n_] := Table[f[k], {k, 1, n}]
    a[n_] := SymmetricPolynomial[n - 1, t[n]]
    Table[a[n], {n, 1, 14}]
    Flatten[{1, Table[Det[Table[BellB[i+j], {i, n}, {j, n}]], {n, 1, 15}]}] (* Vaclav Kotesovec, Nov 28 2016 *)

A204245 Determinant of the n-th principal submatrix of A204244.

Original entry on oeis.org

1, 1, 4, 84, 9792, 7015680, 35334144000, 1424547274752000, 516934658477260800000, 1875850653748811739955200000, 74877948716953984356707205120000000, 35866656974348638336845775173058560000000000
Offset: 1

Views

Author

Clark Kimberling, Jan 13 2012

Keywords

Crossrefs

Programs

  • Mathematica
    f[i_, j_] := 0; f[1, j_] := 1; f[i_, 1] := 1; f[i_, i_] := i!;
    m[n_] := Table[f[i, j], {i, 1, n}, {j, 1, n}]
    TableForm[m[8]] (* 8x8 principal submatrix *)
    Flatten[Table[f[i, n + 1 - i],
      {n, 1, 12}, {i, 1, n}]]      (* A204244 *)
    Table[Det[m[n]], {n, 1, 15}]   (* A204245 *)
    Permanent[m_] :=
      With[{a = Array[x, Length[m]]},
       Coefficient[Times @@ (m.a), Times @@ a]];
    Table[Permanent[m[n]], {n, 1, 14}]   (*  A203228 *)

A204244 Symmetric matrix given by f(i,1)=1, f(1,j)=1, f(i,i)=i! and f(i,j)=0 otherwise.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 0, 0, 1, 1, 0, 6, 0, 1, 1, 0, 0, 0, 0, 1, 1, 0, 0, 24, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 120, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 720, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 5040, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0
Offset: 1

Views

Author

Clark Kimberling, Jan 13 2012

Keywords

Examples

			Northwest corner:
1 1 1 1
1 2 0 0
1 0 6 0
1 0 0 24
		

Crossrefs

Programs

  • Mathematica
    f[i_, j_] := 0; f[1, j_] := 1; f[i_, 1] := 1; f[i_, i_] := i!;
    m[n_] := Table[f[i, j], {i, 1, n}, {j, 1, n}]
    TableForm[m[8]] (* 8x8 principal submatrix *)
    Flatten[Table[f[i, n + 1 - i],
      {n, 1, 12}, {i, 1, n}]]      (* A204244 *)
    Table[Det[m[n]], {n, 1, 15}]   (* A204245 *)
    Permanent[m_] :=
      With[{a = Array[x, Length[m]]},
       Coefficient[Times @@ (m.a), Times @@ a]];
    Table[Permanent[m[n]], {n, 1, 14}]   (*  A203228 *)
Showing 1-3 of 3 results.