A049410 A triangle of numbers related to triangle A049325.

1, 3, 1, 6, 9, 1, 6, 51, 18, 1, 0, 210, 195, 30, 1, 0, 630, 1575, 525, 45, 1, 0, 1260, 10080, 6825, 1155, 63, 1, 0, 1260, 51660, 71505, 21840, 2226, 84, 1, 0, 0, 207900, 623700, 333585, 57456, 3906, 108, 1, 0, 0, 623700, 4573800, 4293135, 1195425, 131670

Offset

1,2

Comments

a(n,1)= A008279(3,n-1). a(n,m)=: S1(-3; n,m), a member of a sequence of lower triangular Jabotinsky matrices, including S1(1; n,m)= A008275 (signed Stirling first kind), S1(2; n,m)= A008297(n,m) (signed Lah numbers). a(n,m) matrix is inverse to signed matrix ((-1)^(n-m))*A000369(n,m).

The monic row polynomials E(n,x) := sum(a(n,m)*x^m,m=1..n), E(0,x) := 1 are exponential convolution polynomials (see A039692 for the definition and a Knuth reference).

Also the inverse Bell transform of the quadruple factorial numbers Product_{k=0..n-1} (4*k+3) (A008545) adding 1,0,0,0,... as column 0. For the definition of the Bell transform see A264428 and for cross-references A265604. - Peter Luschny, Dec 31 2015

Links

Table of n, a(n) for n=1..52.

Wolfdieter Lang, On generalizations of Stirling number triangles, J. Integer Seqs., Vol. 3 (2000), #00.2.4.

Formula

a(n, m) = n!*A049325(n, m)/(m!*4^(n-m)); a(n, m) = (4*m-n+1)*a(n-1, m) + a(n-1, m-1), n >= m >= 1; a(n, m)=0, n<m; a(n, 0) := 0; a(1, 1)=1. E.g.f. for m-th column: (((-1+(1+x)^4)/4)^m)/m!.

Example

Triangle begins:
  {1};
  {3,1};
  {6,9,1};
  {6,51,18,1};
  ...
E.g. row polynomial E(3,x)= 6*x+9*x^2+x^3.

Mathematica

rows = 10;
t = Table[Product[4k+3, {k, 0, n-1}], {n, 0, rows}];
T[n_, k_] := BellY[n, k, t];
M = Inverse[Array[T, {rows, rows}]] // Abs;
A049325 = Table[M[[n, k]], {n, 1, rows}, {k, 1, n}] // Flatten (* Jean-François Alcover, Jun 22 2018, after Peter Luschny *)

Prog

(Sage) # uses[inverse_bell_transform from A265605]
# Adds a column 1, 0, 0, 0, ... at the left side of the triangle.
multifact_4_3 = lambda n: prod(4*k + 3 for k in (0..n-1))
inverse_bell_matrix(multifact_4_3, 9) # Peter Luschny, Dec 31 2015

Crossrefs

Row sums give A049426.

Sequence in context: A257259 A074475 A144877 * A013610 A008573 A089710

Adjacent sequences: A049407 A049408 A049409 * A049411 A049412 A049413

Keyword

easy,nonn,tabl

Author

Wolfdieter Lang

Status

approved