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.

A104600 Number of matrices of any size up to column permutations, with n different elements, zero elsewhere and with no zero row or column.

Original entry on oeis.org

1, 1, 5, 49, 795, 18881, 611193, 25704253, 1356235163, 87419692453, 6741175388313, 611464105166993, 64336296019640307, 7760748741918246361, 1062626712168331953737, 163738827988386433177093, 28181351778805732986601035, 5382075236937341624838444077
Offset: 0

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Author

Ralf Stephan, Mar 27 2005

Keywords

Crossrefs

Row sums of A323128.

Programs

  • Maple
    b:= proc(n, k) option remember; `if`(n=0, 1, add(k!/(k-j)!
          *binomial(n-1, j-1)*b(n-j, k), j=1..min(k, n)))
        end:
    a:= n-> add(add(b(n, k-i)*(-1)^i*binomial(k, i), i=0..k), k=0..n):
    seq(a(n), n=0..21);  # Alois P. Heinz, Sep 03 2019
  • Mathematica
    Table[Sum[StirlingS1[n,k] * Sum[StirlingS2[k,j]*j!,{j,0,k}] * BellB[k],{k,0,n}],{n,0,20}] (* Vaclav Kotesovec, May 03 2015 *)
    Table[1/(2*E) * Sum[Sum[Product[r*s-k,{k,0,n-1}] / (2^r s!),{r,0,Infinity}],{s,0,Infinity}],{n,0,10}] (* Vaclav Kotesovec, May 03 2015 *)

Formula

(1/(2e)) * Sum{r, s>=0, (rs)_n / [2^r s! ] }, where (m)_n is the falling factorial m * (m-1) * ... * (m-n+1).
E.g.f.: exp(-1)*sum(exp((1+x)^n)/2^(n+1),n=0..infinity). - Vladeta Jovovic, Sep 24 2006
a(n) = Sum_{k=0..n} Stirling1(n,k)*A000670(k)*A000110(k). - Vladeta Jovovic, Sep 27 2006
exp(-1)*sum(1/(2-(1+x)^n)/n!,n=0..infinity) is also e.g.f. - Vladeta Jovovic, Oct 09 2006

Extensions

Corrected by Vladeta Jovovic, Sep 08 2006
Offset corrected by Vaclav Kotesovec, May 03 2015