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A000356
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Number of rooted cubic maps with 2n nodes and a distinguished Hamiltonian cycle: (2n)!(2n+1)! / (n!^2*(n+1)!(n+2)!).
(Formerly M3978 N1647)
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12
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1, 5, 35, 294, 2772, 28314, 306735, 3476330, 40831076, 493684828, 6114096716, 77266057400, 993420738000, 12964140630900, 171393565105575, 2291968851019650, 30961684478686500, 422056646314726500
(list;
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OFFSET
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1,2
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COMMENTS
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a(2n-1) is also the sum of the numbers of standard Young tableaux of size 2n+1 and of shapes (k+3,k+2,2^{n-2-k}), 0 <= k <= n-2. - Amitai Regev (amitai.regev(AT)weizmann.ac.il), Mar 10 2010
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REFERENCES
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Amitai Regev, Preprint. [From Amitai Regev (amitai.regev(AT)weizmann.ac.il), Mar 10 2010]
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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Vincenzo Librandi, Table of n, a(n) for n = 1..800
R. K. Guy, Catwalks, sandsteps and Pascal pyramids, J. Integer Sequences, Vol. 3 (2000), Article #00.1.6.
Anatol N. Kirillov, Notes on Schubert, Grothendieck and key polynomials, SIGMA, Symmetry Integrability Geom. Methods Appl. 12, Paper 034, 56 p. (2016).
W. T. Tutte, A census of Hamiltonian polygons, Canad. J. Math., 14 (1962), 402-417.
W. T. Tutte, On the enumeration of four-colored maps, SIAM J. Appl. Math., 17 (1969), 454-460.
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FORMULA
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G.f.: (with offset 0) 3F2( [1, 3/2, 5/2], [3, 4], 16*x) = (1 - 2*x - 2F1( [-1/2, 1/2], [2], 16*x) ) / (4*x^2). - Olivier Gérard, Feb 16 2011
a(n)*(n+2) = A000891(n). - Gary W. Adamson, Apr 08 2011
D-finite with recurrence (n+2)*(n+1)*a(n)-4*(2*n-1)*(2*n+1)*a(n-1)=0. - R. J. Mathar, Mar 03 2013
From Ilya Gutkovskiy, Feb 01 2017: (Start)
E.g.f.: (1/2)*(2F2(1/2,3/2; 2,3; 16*x) - 1).
a(n) ~ 2^(4*n+1)/(Pi*n^3). (End)
From Peter Bala, Feb 22 2023: (Start)
a(n) = Product_{1 <= i <= j <= n-1} (i + j + 3)/(i + j - 1).
a(n) = (2^(n-1)) * Product_{1 <= i <= j <= n-1} (i + j + 3)/(i + j) for n >= 1.
Cf. A003645. (End)
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MAPLE
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A000356 := proc(n)
binomial(2*n, n)*binomial(2*n+1, n+1)/(n+1)/(n+2) ;
end proc:
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MATHEMATICA
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CoefficientList[ Series[1 + (HypergeometricPFQ[{1, 3/2, 5/2}, {3, 4}, 16 x] - 1), {x, 0, 17}], x]
Table[(2*n)!*(2*n+2)!/(2*n!*(n+1)!^2*(n+2)!), {n, 30}] (* Vincenzo Librandi, Mar 25 2012 *)
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CROSSREFS
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Cf. A000264, A000309.
Equals A005568/2.
Fourth row of array A102539.
Column of array A073165.
Image of A001700 under the "little Hankel" transform (see A056220 for definition). - John W. Layman, Aug 22 2000
Cf. A000891.
Sequence in context: A248053 A002294 A051406 * A027392 A291813 A346765
Adjacent sequences: A000353 A000354 A000355 * A000357 A000358 A000359
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KEYWORD
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easy,nonn,nice
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AUTHOR
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N. J. A. Sloane, Simon Plouffe
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EXTENSIONS
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Better definition from Michael Albert, Oct 24 2008
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STATUS
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approved
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