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 A052786 A simple grammar. 0
 0, 0, 0, 0, 0, 0, 720, 7560, 70560, 680400, 7015680, 78004080, 935542080, 12074119200, 167122859904, 2472036446880, 38940240568320, 651087633530880, 11519998092877824, 215088381671892480 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,7 LINKS INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 743 FORMULA E.g.f.: x^3*log(-1/(-1+x))^3. Recurrence: {a(1)=0, a(2)=0, a(4)=0, a(3)=0, a(5)=0, a(6)=720, (16*n^4+135*n+162-81*n^2-42*n^3-n^6+3*n^5)*a(n) + (-228+81*n^2+3*n^5+104*n-38*n^3-6*n^4)*a(n+1) + (36+6*n^3-3*n^4+21*n^2-60*n)*a(n+2) + (-3*n^2+n^3+2*n)*a(n+3)}. MAPLE spec := [S, {B=Cycle(Z), S=Prod(Z, Z, Z, B, B, B)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20); CROSSREFS Sequence in context: A029574 A119540 A052784 * A187192 A052792 A052790 Adjacent sequences:  A052783 A052784 A052785 * A052787 A052788 A052789 KEYWORD easy,nonn AUTHOR encyclopedia(AT)pommard.inria.fr, Jan 25 2000 STATUS approved

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