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 A054558 Number of labeled pure 2-complexes on n nodes (0-simplexes) with 5 2-simplexes and 9 1-simplexes. 1
 150, 960, 3605, 10360, 25200, 54600, 108570, 201960, 356070, 600600, 975975, 1536080, 2351440, 3512880, 5135700, 7364400, 10377990, 14395920, 19684665, 26565000, 35420000, 46703800, 60951150, 78787800, 100941750, 128255400 (list; graph; refs; listen; history; text; internal format)
 OFFSET 5,1 COMMENTS Number of {T_1,T_2,...,T_k} where T_i, i=1..k are 3-subsets of an n-set such that {D | D is 2-subset of T_i for some i=1..k} has l elements; k=5, l=9. REFERENCES V. Jovovic, On the number of two-dimensional simplicial complexes (in Russian), Metody i sistemy tekhnicheskoy diagnostiki, Vypusk 16, Mezhvuzovskiy zbornik nauchnykh trudov, Izdatelstvo Saratovskogo universiteta, 1991. LINKS Table of n, a(n) for n=5..30. Index entries for linear recurrences with constant coefficients, signature (8,-28,56,-70,56,-28,8,-1). FORMULA a(n) = 150*C(n,5) +60*C(n,6) +35*C(n,7) = n*(n-1)*(n-2)*(n-3)*(n-4)*(n^2+n+150)/144. G.f.: 5*x^5*(30-48*x+25*x^2)/(1-x)^8. - Colin Barker, Jun 21 2012 MAPLE A054558:=n->n*(n-1)*(n-2)*(n-3)*(n-4)*(n^2+n+150)/144; seq(A054558(n), n=5..30); # Wesley Ivan Hurt, Apr 29 2014 MATHEMATICA Table[n*(n - 1)*(n - 2)*(n - 3)*(n - 4)*(n^2 + n + 150)/144, {n, 5, 30}] (* Wesley Ivan Hurt, Apr 29 2014 *) CROSSREFS Cf. A054557. Sequence in context: A273322 A206066 A140671 * A250544 A251801 A211554 Adjacent sequences: A054555 A054556 A054557 * A054559 A054560 A054561 KEYWORD nonn,easy AUTHOR Vladeta Jovovic, Apr 10 2000 STATUS approved

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Last modified April 24 04:14 EDT 2024. Contains 371918 sequences. (Running on oeis4.)