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.

A137375 Triangle read by rows, T(n,k) = (-1)^k*{{n,k}} where {{n,k}} are the second-order Stirling set numbers, n>=0, 0<=k<=n/2.

Original entry on oeis.org

1, 0, 0, -1, 0, -1, 0, -1, 3, 0, -1, 10, 0, -1, 25, -15, 0, -1, 56, -105, 0, -1, 119, -490, 105, 0, -1, 246, -1918, 1260, 0, -1, 501, -6825, 9450, -945, 0, -1, 1012, -22935, 56980, -17325, 0, -1, 2035, -74316, 302995, -190575, 10395, 0, -1, 4082, -235092
Offset: 0

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Author

Roger L. Bagula, Apr 09 2008

Keywords

Comments

Also called "associated Stirling numbers of the second kind" by Riordan in the signless form with different offset A008299.
Old name was: Triangular sequence from coefficients of Mahler polynomials from expansion of: p(x) = exp(x*(1 + t - exp(t))) with weight n!:M(x,n).
M(n,x) = sum(k=0..n, (x)^k*sum(j=0..k, binomial(n,k-j)*stirling2(n-k+j,j)*(-1)^j)). - Vladimir Kruchinin, Jan 13 2012

Examples

			[ 0]  1;
[ 1]  0;
[ 2]  0, -1;
[ 3]  0, -1;
[ 4]  0, -1,   3;
[ 5]  0, -1,  10;
[ 6]  0, -1,  25,   -15;
[ 7]  0, -1,  56,  -105;
[ 8]  0, -1, 119,  -490,  105;
[ 9]  0, -1, 246, -1918, 1260;
[10]  0, -1, 501, -6825, 9450, -945;
		

References

  • J. Riordan, Introduction to Combinatory Analysis, Wiley, New York, 1958.

Crossrefs

Row sums are: A000587.

Programs

  • Maple
    A137375 := proc(n, k) if n = 0 then 1 else
    add(binomial(j,n-2*k)* combinat[eulerian2](n-k,n-k-j-1), j=(0..n-k-1))*(-1)^k fi end: for n from 0 to 9 do seq(A137375(n, k), k=(0..n/2)) od; # Peter Luschny, Dec 01 2012
  • Mathematica
    Clear[p, x, t] p[t_] = Exp[x*(1 + t - Exp[t])]; Table[ ExpandAll[n!* SeriesCoefficient[Series[p[t], {t, 0, 30}], n]], {n, 0, 10}] a = Table[ CoefficientList[n!*SeriesCoefficient[Series[p[t], {t, 0, 30}], n], x], {n, 0, 10}]; Flatten[a];
    Table[Sum[Binomial[n, k - j] StirlingS2[n - k + j, j] (-1)^j, {j, 0, k}], {n, 0, 15}, {k, 0, n/2}] // Flatten (* Eric W. Weisstein, Nov 13 2018 *)
  • Maxima
    T(n,k):=sum(binomial(n,k-j)*stirling2(n-k+j,j)*(-1)^(j),j,0,k); /* Vladimir Kruchinin, Jan 13 2012 */
    
  • Sage
    def A137375(n, k): return add(binomial(n,k-j)*(-1)^j*stirling_number2(n-k+j,j) for j in (0..k))
    for n in range(11):
        [A137375(n, k) for k in (0..n//2)]  # Peter Luschny, Dec 01 2012

Formula

T(n,k) = Sum_{j=0..k} C(n,k-j)*stirling2(n-k+j,j)*(-1)^(j). - Vladimir Kruchinin, Jan 13 2012
T(n,k) = (-1)^k*Sum_{j=0..n-k} C(j,n-2*k)*E2(n-k,n-k-j-1) for n>0, T(0,0) = 1, where E2(n,k) are the second-order Eulerian numbers A201637. - Peter Luschny, Nov 27 2012
Let p(x,t) = exp(x*(1+t-exp(t))) then T(n,k) = [x^k](n!*[t^n] series(p(x,t))) where [s^m] denotes the coefficient of s^m. - Peter Luschny, Dec 01 2012

Extensions

Edited and simpler definition by Peter Luschny, Nov 27 2012