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.

A201636 Triangle read by rows, n>=0, k>=0, T(0,0) = 1, T(n,k) = Sum_{j=0..k} (C(n+k,k-j)*(-1)^(k-j)*2^(n-j)*Sum_{i=0..j} (C(n+j,i)*|S(n+j-i,j-i)|)), S = Stirling number of first kind.

Original entry on oeis.org

1, 0, 1, 0, 4, 3, 0, 24, 40, 15, 0, 192, 520, 420, 105, 0, 1920, 7392, 9520, 5040, 945, 0, 23040, 116928, 211456, 176400, 69300, 10395, 0, 322560, 2055168, 4858560, 5642560, 3465000, 1081080, 135135, 0, 5160960, 39896064, 117722880, 177580480, 150870720, 73153080, 18918900, 2027025
Offset: 0

Views

Author

Peter Luschny, Nov 13 2012

Keywords

Comments

This triangle was inspired by a formula of Vladimir Kruchinin given in A001662.

Examples

			[n\k 0,    1,    2,    3,    4,   5]
[0]  1,
[1]  0,    1,
[2]  0,    4,    3,
[3]  0,   24,   40,   15,
[4]  0,  192,  520,  420,  105,
[5]  0, 1920, 7392, 9520, 5040, 945,
		

Crossrefs

Programs

  • Maple
    A201636 := proc(n,k) if n=0 and k=0 then 1 else
    add(binomial(n+k,k-j)*(-1)^(n+k-j)*2^(n-j)*
    add(binomial(n+j,i)*stirling1(n+j-i,j-i),i=0..j),j=0..k) fi end:
    for n from 0 to 8 do print(seq(A201636(n,k),k=0..n)) od;
  • Mathematica
    T[0, 0] = 1; T[n_, k_] := T[n, k] = Sum[Binomial[n+k, k-j]*(-1)^(n+k-j)* 2^(n-j)*Sum[Binomial[n+j, i]*StirlingS1[n+j-i, j-i], {i, 0, j}], {j, 0, k}];
    Table[T[n, k], {n, 0, 8}, {k, 0, n}] (* Jean-François Alcover, Jun 29 2019 *)
  • Sage
    def A201636(n,k) :
        if n==0 and k==0: return 1
        return add(binomial(n+k,k-j)*(-1)^(k-j)*2^(n-j)*add(binomial(n+j,i)* stirling_number1(n+j-i,j-i) for i in (0..j)) for j in (0..k))

Formula

T(n,1) = A002866(n) for n>0.
T(n,n) = A001147(n).
Sum((-1)^(n-k)*T(n,k)) = A001662(n+1).