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.

A176663 T(n, k) = [x^k] Sum_{j=0..n} j!*binomial(x, j), for 0 <= k <= n, triangle read by rows.

Original entry on oeis.org

1, 1, 1, 1, 0, 1, 1, 2, -2, 1, 1, -4, 9, -5, 1, 1, 20, -41, 30, -9, 1, 1, -100, 233, -195, 76, -14, 1, 1, 620, -1531, 1429, -659, 161, -20, 1, 1, -4420, 11537, -11703, 6110, -1799, 302, -27, 1, 1, 35900, -98047, 106421, -61174, 20650, -4234, 519, -35, 1
Offset: 0

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Author

Roger L. Bagula, Apr 23 2010

Keywords

Examples

			Triangle starts:
  {1},
  {1,       1},
  {1,       0,      1},
  {1,       2,     -2,        1},
  {1,      -4,      9,       -5,      1},
  {1,      20,    -41,       30,     -9,       1},
  {1,    -100,    233,     -195,     76,     -14,     1},
  {1,     620,  -1531,     1429,   -659,     161,   -20,     1},
  {1,   -4420,  11537,   -11703,   6110,   -1799,   302,   -27,   1},
  {1,   35900, -98047,   106421, -61174,   20650, -4234,   519, -35,   1},
  {1, -326980, 928529, -1066279, 662506, -248675, 59039, -8931, 835, -44, 1}
		

Crossrefs

Row sums are A040000. Alternating row sums are A058006, which are also T(n,1).
Cf. A186020.

Programs

  • Maple
    with(PolynomialTools):
    T_row := n -> CoefficientList(expand(add(k!*binomial(x, k), k=0..n)), x):
    ListTools:-Flatten([seq(T_row(n), n=0..9)]); # Peter Luschny, Jul 02 2019
  • Mathematica
    p[x_, n_] := Sum[k! Binomial[x, k], {k, 0, n}];
    Table[CoefficientList[FunctionExpand[p[x, n]], x], {n, 0, 10}] // Flatten
    (* Alternative: *)
    Table[CoefficientList[FunctionExpand[Sum[FactorialPower[x, k], {k, 0, n}]], x], {n, 0, 10}] // Flatten (* Peter Luschny, Jul 02 2019 *)

Formula

From Peter Luschny, Jul 02 2019: (Start)
Sum_{k=0..n} T(n, k)*x^k = Sum_{k=0..n} (x)_k, where (x)_k denotes the falling factorial.
Let T be the lower triangular matrix associated to the T(n, k) and S the lower triangular matrix associated to the Stirling set numbers S2(n, k). Then S*T = A186020 (seen as a matrix) and T*S = A000012 (seen as a matrix). (End)
T(n, k) = Sum_{i=0..n-k} Stirling1(i+k, k). - Igor Victorovich Statsenko, May 25 2024

Extensions

Edited by Peter Luschny, Jul 02 2019