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 A094219 Number of permutations of length n with exactly 3 occurrences of the pattern 2-13. 8
 0, 0, 0, 0, 7, 112, 1092, 8400, 56100, 341088, 1939938, 10498488, 54679625, 276276000, 1362040680, 6580248480, 31256180280, 146350008000, 676868787000, 3097351569312, 14042319855102, 63144549413792, 281895309883000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,5 REFERENCES R. Lie, Permutations and Patterns, Master's Thesis, Goeteborg, Sweden: Chalmers University of Technology, 2004. LINKS Alois P. Heinz, Table of n, a(n) for n = 1..500 R. Parviainen, Lattice Path Enumeration of Permutations with k Occurrences of the Pattern 2-13, Journal of Integer Sequences, Vol. 9 (2006), Article 06.3.2. FORMULA a(n) = (1/3)*binomial(n+2,2)*binomial(2*n,n-5). G.f.: (-7*x^2+8*x-2-(4*x^7+14*x^6+84*x^5-350*x^4+350*x^3-147*x^2+28*x-2) /(1-4*x)^(5/2)) /(2*x^5). - Mark van Hoeij, Apr 30 2013 MATHEMATICA Table[Binomial[n + 2, 2] Binomial[2 n, n - 5]/3, {n, 1, 30}] (* Vincenzo Librandi, Aug 20 2015 *) PROG (PARI) a(n)=1/3*binomial(n+2, 2)*binomial(2*n, n-5) (MAGMA) [(1/3)*Binomial(n+2, 2)*Binomial(2*n, n-5): n in [1..30]]; // Vincenzo Librandi, Aug 20 2015 CROSSREFS Cf. A094218. Column k=3 of A263776. Sequence in context: A061233 A117795 A163700 * A212702 A217223 A067404 Adjacent sequences:  A094216 A094217 A094218 * A094220 A094221 A094222 KEYWORD nonn AUTHOR Benoit Cloitre, May 27 2004 STATUS approved

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Last modified April 6 12:19 EDT 2020. Contains 333273 sequences. (Running on oeis4.)