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 A052619 E.g.f. 3x^3/(1-x). 0
 0, 0, 0, 18, 72, 360, 2160, 15120, 120960, 1088640, 10886400, 119750400, 1437004800, 18681062400, 261534873600, 3923023104000, 62768369664000, 1067062284288000, 19207121117184000, 364935301226496000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 LINKS INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 564 FORMULA E.g.f.: -3*x^3/(-1+x) Recurrence: {a(1)=0, a(0)=0, a(2)=0, (-1-n)*a(n)+a(n+1)=0, a(3)=18} 3*n!, n>2. E.g.f. G(0)*3*x^3 where G(k)= 1 + x/(1 - x/( x + 1/G(k+1))); (continued fraction, 3rd kind, 3-step). - Sergei N. Gladkovskii, Jul 28 2012 MAPLE spec := [S, {S=Prod(Z, Z, Sequence(Z), Union(Z, Z, Z))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20); CROSSREFS Sequence in context: A069058 A262000 A007276 * A110753 A154670 A041626 Adjacent sequences:  A052616 A052617 A052618 * A052620 A052621 A052622 KEYWORD easy,nonn AUTHOR encyclopedia(AT)pommard.inria.fr, Jan 25 2000 STATUS approved

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Last modified September 20 00:58 EDT 2021. Contains 347577 sequences. (Running on oeis4.)