A268437 Triangle read by rows, T(n,k) = (-1)^k*(2*n)!*P[n,k](1/(n+1)) where P is the P-transform, for n>=0 and 0<=k<=n.

1, 0, 1, 0, 4, 6, 0, 30, 120, 90, 0, 336, 2800, 5040, 2520, 0, 5040, 80640, 264600, 302400, 113400, 0, 95040, 2827440, 15190560, 29937600, 24948000, 7484400, 0, 2162160, 118198080, 983782800, 2986663680, 4162158000, 2724321600, 681080400

Offset

0,5

Comments

The P-transform is defined in the link. Compare also the Sage and Maple implementations below.

Links

Table of n, a(n) for n=0..35.

Peter Luschny, The P-transform.

Formula

T(n,k) = ((2*n)!/FF(n+k,n))*Sum_{m=0..k}(-1)^(m+k)*C(n+k,n+m)*Stirling2(n+m,m) where FF denotes the falling factorial function.

T(n,k) = ((2*n)!/FF(n+k,n))*A269939(n,k).

T(n,1) = (2*n)!/(n+1)! = A001761(n) for n>=1.

T(n,n) = (2*n)!/2^n = A000680(n) for n>=0.

Example

[1],
[0, 1],
[0, 4, 6],
[0, 30, 120, 90],
[0, 336, 2800, 5040, 2520],
[0, 5040, 80640, 264600, 302400, 113400],
[0, 95040, 2827440, 15190560, 29937600, 24948000, 7484400].

Maple

A268437 := proc(n, k) local F, T;
  F := proc(n, k) option remember;
  `if`(n=0 and k=0, 1, `if`(n=k, (4*n-2)*F(n-1, k-1),
  F(n-1, k)*(n+k))) end;
  T := proc(n, k) option remember;
  `if`(k=0 and n=0, 1, `if`(k<=0 or k>n, 0,
  (4*n-2)*n*(k*T(n-1, k)+(n+k-1)*T(n-1, k-1)))) end;
T(n, k)/F(n, k) end:
for n from 0 to 6 do seq(A268437(n, k), k=0..n) od;
# Alternatively, with the function PTrans defined in A269941:
A268437_row := n -> PTrans(n, n->1/(n+1), (n, k)->(-1)^k*(2*n)!):
seq(print(A268437_row(n)), n=0..8);

Mathematica

T[n_, k_] := (2n)!/FactorialPower[n+k, n] Sum[(-1)^(m+k) Binomial[n+k, n+m] StirlingS2[n+m, m], {m, 0, k}];
Table[T[n, k], {n, 0, 7}, {k, 0, n}] (* Jean-François Alcover, Jun 15 2019 *)

Prog

(Sage)
A268437 = lambda n, k: (factorial(2*n)/falling_factorial(n+k, n))*sum((-1)^(m+k)* binomial(n+k, n+m)*stirling_number2(n+m, m) for m in (0..k))
for n in (0..7): print([A268437(n, m) for m in (0..n)])
(Sage) # uses[PtransMatrix from A269941]
PtransMatrix(8, lambda n: 1/(n+1), lambda n, k: (-1)^k* factorial(2*n))

Crossrefs

Cf. A000680, A001761, A268438, A269939, A269941.

Sequence in context: A285584 A316386 A288422 * A265685 A111828 A013249

Adjacent sequences: A268434 A268435 A268436 * A268438 A268439 A268440

Keyword

nonn,tabl

Author

Peter Luschny, Mar 07 2016

Status

approved