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A243667 Number of Sylvester classes of 4-packed words of degree n. 4
1, 1, 6, 50, 484, 5105, 56928, 660112, 7878940, 96159476, 1194532794, 15053992178, 191993403476, 2473358617150, 32137897641232, 420698195672700, 5542894551818268, 73447821835338348, 978178443083177880, 13086377223959022952, 175785879063917657688 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

See Novelli-Thibon (2014) for precise definition.

LINKS

Seiichi Manyama, Table of n, a(n) for n = 0..865

J.-C. Novelli, J.-Y. Thibon, Hopf Algebras of m-permutations,(m+1)-ary trees, and m-parking functions, arXiv preprint arXiv:1403.5962 [math.CO], 2014. See Eq. (185), p. 47 and Fig. 17.

FORMULA

Novelli-Thibon give an explicit formula in Eq. (182).

From Seiichi Manyama, Jul 26 2020: (Start)

G.f. A(x) satisfies: A(x) = 1 - x * A(x)^4 * (1 -  2 * A(x)).

a(n) = (-1)^n * Sum_{k=0..n} (-2)^k * binomial(n,k) * binomial(4*n+k+1,n)/(4*n+k+1).

a(n) = ( (-1)^n / (4*n+1) ) * Sum_{k=0..n} (-2)^(n-k) * binomial(4*n+1,k) * binomial(5*n-k,n-k). (End)

MATHEMATICA

P[n_, m_, x_] := 1/(m n + 1) Sum[Binomial[m n + 1, k] Binomial[(m + 1) n - k, n - k] (1 - x)^k x^(n - k), {k, 0, n}];

a[n_] := P[n, 4, 2];

a /@ Range[20] (* Jean-François Alcover, Jan 28 2020 *)

PROG

(PARI) {a(n) = local(A=1+x*O(x^n)); for(i=0, n, A=1-x*A^4*(1-2*A)); polcoeff(A, n)} \\ Seiichi Manyama, Jul 26 2020

(PARI) {a(n) = (-1)^n*sum(k=0, n, (-2)^k*binomial(n, k)*binomial(4*n+k+1, n)/(4*n+k+1))} \\ Seiichi Manyama, Jul 26 2020

(PARI) {a(n) = (-1)^n*sum(k=0, n, (-2)^(n-k)*binomial(4*n+1, k)*binomial(5*n-k, n-k))/(4*n+1)} \\ Seiichi Manyama, Jul 26 2020

CROSSREFS

Column k=4 of A336573.

Cf. A243668, A336572.

Sequence in context: A180910 A199680 A039742 * A303562 A125558 A005416

Adjacent sequences:  A243664 A243665 A243666 * A243668 A243669 A243670

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Jun 14 2014

EXTENSIONS

More terms from Jean-François Alcover, Jan 28 2020

a(0)=1 prepended by Seiichi Manyama, Jul 25 2020

STATUS

approved

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Last modified November 25 11:32 EST 2020. Contains 338623 sequences. (Running on oeis4.)