A052770 A simple grammar.

0, 0, 0, 0, 0, 120, 1440, 14280, 141120, 1462104, 16148160, 191051520, 2421936000, 32840519712, 475109002368, 7312951114560, 119419875993600, 2063254247160192, 37617587514390528, 721991172931734528

Offset

0,6

Links

Table of n, a(n) for n=0..19.

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 727

Formula

E.g.f.: log(-1/(-1+x))^4*x.

Recurrence: {a(1)=0, a(2)=0, a(4)=0, a(3)=0, (n^8+6*n^7-46*n-21*n^2-5*n^4-34*n^5+24+74*n^3+n^6)*a(n) + (-4*n^7+49*n^3-70*n^2+25*n^4-54*n^5-30*n^6+24*n)*a(n+1) + (115*n^4+48*n^5+6*n^6+19*n^2+12*n+80*n^3)*a(n+2) + (-16*n-70*n^3-60*n^2-30*n^4-4*n^5)*a(n+3) + (n^4+6*n^3+11*n^2+6*n)*a(n+4), a(5)=120}.

Maple

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

Crossrefs

Sequence in context: A348216 A167549 A052776 * A175112 A257996 A183597

Adjacent sequences: A052767 A052768 A052769 * A052771 A052772 A052773

Keyword

easy,nonn

Author

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

Status

approved