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 A069039 Expansion of x(1+x)^5/(1-x)^7. 13
 0, 1, 12, 73, 304, 985, 2668, 6321, 13504, 26577, 48940, 85305, 142000, 227305, 351820, 528865, 774912, 1110049, 1558476, 2149033, 2915760, 3898489, 5143468, 6704017, 8641216, 11024625, 13933036, 17455257, 21690928, 26751369, 32760460 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Figurate numbers based on the 6-dimensional regular convex polytope called the 6-dimensional cross-polytope, or 6-dimensional hyperoctahedron, which is represented by the Schlaefli symbol {3, 3, 3, 3, 4}. It is the dual of the 6-dimensional hypercube. Kim asserts that every nonnegative integer can be represented by the sum of no more than 19 of these 6-crosspolytope numbers. - Jonathan Vos Post, Nov 16 2004 Starting with 1 = binomial transform of [1, 11, 50, 120, 160, 112, 32, 0, 0, 0,...] where (1, 11, 50, 120, 160, 112, 32) = row 6 of the Chebyshev triangle A081277. Also = row 6 of the array in A142978. - Gary W. Adamson, Jul 19 2008 REFERENCES H. S. M. Coxeter, Regular Polytopes, New York: Dover, 1973. E. Deza and M. M. Deza, Figurate numbers, World Scientific Publishing (2012), page 240. J. V. Post, "4-Dimensional Jonathan numbers: polytope numbers and Centered polytope numbers of Higher Than 3 Dimensions", Draft 1.5 of 9 a.m., 12 March 2004, circulated by e-mail. LINKS Seiichi Manyama, Table of n, a(n) for n = 0..10000 M. Janjic and B. Petkovic, A Counting Function, arXiv 1301.4550 [math.CO], 2013. Hyun Kwang Kim, On Regular Polytope Numbers, Proc. Amer. Math. Soc., 131 (2003), 65-75. J. V. Post, Table of polytope numbers, Sorted, Through 1,000,000. J. V. Post, Math Pages. Index entries for linear recurrences with constant coefficients, signature (7,-21,35,-35,21,-7,1). FORMULA Recurrence: a(n) = 7*a(n-1)-21*a(n-2)+35*a(n-3)-35*a(n-4)+21*a(n-5)-7*a(n-6)+a(n-7). a(n) = 6-crosspolytope(n) = (n^2)*(2*n^4 + 20*n^2 + 23 )/45. E.g. a(12) = 142000 because (12^2)*(2*12^4 + 20*12^2 + 23 )/45. - Jonathan Vos Post, Nov 16 2004 From Stephen Crowley, Jul 14 2009: (Start) Sum_{n >= 1} 1/a(n) = -5*(Sum(_alpha*(77*_alpha^2+655)*Psi(1-_alpha), _alpha = RootOf(2*_Z^4+20*_Z^2+23)))*(1/3174)+15*Pi^2*(1/46)=1.10203455013915915542552577192042916250524... Sum_{n>=1} 1/(a(n)*n!) = hypergeom([1, 1, 1, 1-a, 1+b, 1-b, 1+a], [2, 2, 2, 2+b, 2-b, 2+a, 2-a], 1) = 1.04409584723862654376639417281585634150689... where a = I*sqrt(20+6*sqrt(6))*(1/2) and b = I*sqrt(20-6*sqrt(6))*(1/2). (End) a(n) = 12*a(n-1)/(n-1) + a(n-2) for n > 1. - Seiichi Manyama, Jun 06 2018 MAPLE al:=proc(s, n) binomial(n+s-1, s); end; be:=proc(d, n) local r; add( (-1)^r*binomial(d-1, r)*2^(d-1-r)*al(d-r, n), r=0..d-1); end; [seq(be(6, n), n=0..100)]; MATHEMATICA a[n_] := n^2*(2*n^4 + 20*n^2 + 23)/45; Table[a[n], {n, 0, 30}] (* Jean-François Alcover, Jan 29 2014 *) CoefficientList[Series[x (1+x)^5/(1-x)^7, {x, 0, 40}], x] (* or *) LinearRecurrence[ {7, -21, 35, -35, 21, -7, 1}, {0, 1, 12, 73, 304, 985, 2668}, 40] (* Harvey P. Dale, Aug 05 2018 *) PROG (PARI) x='x+O('x^100); concat(0, Vec(x*(1+x)^5/(1-x)^7)) \\ Altug Alkan, Dec 14 2015 CROSSREFS Similar sequence: A005900 (m=3), A014820(n-1) (m=4), A069038 (m=5), A099193 (m=7), A099195 (m=8), A099196 (m=9), A099197 (m=10). Cf. A000332. Cf. A081277, A142978. Sequence in context: A120783 A103475 A024014 * A156196 A041270 A055912 Adjacent sequences:  A069036 A069037 A069038 * A069040 A069041 A069042 KEYWORD nonn,easy AUTHOR Vladeta Jovovic, Apr 03 2002 STATUS approved

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Last modified May 20 02:22 EDT 2019. Contains 323411 sequences. (Running on oeis4.)