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 A003519 a(n) = 10*C(2n+1, n-4)/(n+6). (Formerly M4721) 23
 1, 10, 65, 350, 1700, 7752, 33915, 144210, 600875, 2466750, 10015005, 40320150, 161280600, 641886000, 2544619500, 10056336264, 39645171810, 155989499540, 612815891050, 2404551645100, 9425842448792, 36921502679600, 144539291740025, 565588532895750, 2212449261033375 (list; graph; refs; listen; history; text; internal format)
 OFFSET 4,2 COMMENTS Number of standard tableaux of shape (n+5,n-4). - Emeric Deutsch, May 30 2004 a(n) is the number of North-East paths from (0,0) to (n,n) that cross the diagonal y = x horizontally exactly twice. By symmetry, it is also the number of North-East paths from (0,0) to (n,n) that cross the diagonal y = x vertically exactly twice. Details can be found in Section 3.3 in Pan and Remmel's link. - Ran Pan, Feb 02 2016 REFERENCES N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS Robert Israel, Table of n, a(n) for n = 4..1650 Daniel Birmajer, Juan B. Gil and Michael D. Weiner, Bounce statistics for rational lattice paths, arXiv:1707.09918 [math.CO], 2017, p. 9. Richard K. Guy, Letter to N. J. A. Sloane, May 1990. Richard K. Guy, Catwalks, sandsteps and Pascal pyramids, J. Integer Sequences, Vol. 3 (2000), Article #00.1.6. V. E. Hoggatt, Jr., 7-page typed letter to N. J. A. Sloane with suggestions for new sequences, circa 1977. V. E. Hoggatt, Jr. and M. Bicknell, Catalan and related sequences arising from inverses of Pascal's triangle matrices, Fib. Quart., Vol. 14, No. 5 (1976), pp. 395-405. Ran Pan and Jeffrey B. Remmel, Paired patterns in lattice paths, arXiv:1601.07988 [math.CO], 2016. FORMULA G.f.: x^4*C(x)^10, where C(x)=[1-sqrt(1-4x)]/(2x) is g.f. for the Catalan numbers (A000108). - Emeric Deutsch, May 30 2004 Let A be the Toeplitz matrix of order n defined by: A[i,i-1]=-1, A[i,j]=Catalan(j-i), (i<=j), and A[i,j]=0, otherwise. Then, for n>=9, a(n-5)=(-1)^(n-9)*coeff(charpoly(A,x),x^9). [Milan Janjic, Jul 08 2010] a(n) = A214292(2*n,n-5) for n > 4. - Reinhard Zumkeller, Jul 12 2012 From Robert Israel, Feb 02 2016: (Start) D-finite with recurrence a(n+1) = 2*(n+1)*(2n+3)/((n+7)*(n-3)) * a(n). a(n) ~ 20 * 4^n/sqrt(Pi*n^3). (End) E.g.f.: 5*BesselI(5,2*x)*exp(2*x)/x. - Ilya Gutkovskiy, Jan 23 2017 From Amiram Eldar, Jan 02 2022: (Start) Sum_{n>=4} 1/a(n) = 34*Pi/(45*sqrt(3)) - 44/175. Sum_{n>=4} (-1)^n/a(n) = 53004*log(phi)/(125*sqrt(5)) - 79048/875, where phi is the golden ratio (A001622). (End) MAPLE seq(10*binomial(2*n+1, n-4)/(n+6), n=4..50); # Robert Israel, Feb 02 2016 MATHEMATICA Table[10 Binomial[2 n + 1, n - 4]/(n + 6), {n, 4, 28}] (* Michael De Vlieger, Feb 03 2016 *) PROG (PARI) a(n) = 10*binomial(2*n+1, n-4)/(n+6); \\ Michel Marcus, Feb 02 2016 (Magma) [10*Binomial(2*n+1, n-4)/(n+6): n in [4..35]]; // Vincenzo Librandi, Feb 03 2016 CROSSREFS A diagonal of any of the essentially equivalent arrays A009766, A030237, A033184, A059365, A099039, A106566, A130020, A047072. Cf. A000108, A000245, A002057, A000344, A003517, A000588, A003518, A001392, A001622. Sequence in context: A354393 A346976 A354397 * A056280 A000453 A327505 Adjacent sequences: A003516 A003517 A003518 * A003520 A003521 A003522 KEYWORD nonn,easy AUTHOR STATUS approved

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Last modified March 31 04:26 EDT 2023. Contains 361627 sequences. (Running on oeis4.)