A052768 A simple grammar.

0, 0, 0, 0, 0, 120, 360, 840, 1680, 3024, 5040, 7920, 11880, 17160, 24024, 32760, 43680, 57120, 73440, 93024, 116280, 143640, 175560, 212520, 255024, 303600, 358800, 421200, 491400, 570024, 657720, 755160, 863040, 982080, 1113024

Offset

0,6

Links

Table of n, a(n) for n=0..34.

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 725

Index entries for linear recurrences with constant coefficients, signature (5,-10,10,-5,1).

Formula

a(n)=0, n <= 4; a(n) = n*(n-1)*(n-2)*(n-3), n >= 5.

G.f.: 24*x^5*(5-10*x+10*x^2-5*x^3+x^4)/(1-x)^5. [Colin Barker, Jun 25 2012]

Maple

spec := [S, {B=Set(Z, 1 <= card), S=Prod(Z, Z, Z, Z, B)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);

Crossrefs

Sequence in context: A118058 A269037 A144524 * A242845 A234915 A061218

Adjacent sequences: A052765 A052766 A052767 * A052769 A052770 A052771

Keyword

easy,nonn

Author

encyclopedia(AT)pommard.inria.fr, Jan 25 2000

Extensions

More terms and corrected formula from Larry Reeves (larryr(AT)acm.org), Jan 23 2001

Status

approved