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A000504
S2(j,2j+3) where S2(n,k) is a 2-associated Stirling number of the second kind.
(Formerly M5315 N2309)
1
1, 56, 1918, 56980, 1636635, 47507460, 1422280860, 44346982680, 1446733012725, 49473074851200, 1774073543492250, 66681131440423500, 2624634287988087375, 108060337458000427500, 4647703259223579555000, 208548093035794902390000, 9749651260035434678555625
OFFSET
1,2
REFERENCES
L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 256.
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).
F. N. David and D. E. Barton, Combinatorial Chance. Hafner, NY, 1962, p. 296.
LINKS
H. W. Gould, Harris Kwong, Jocelyn Quaintance, On Certain Sums of Stirling Numbers with Binomial Coefficients, J. Integer Sequences, 18 (2015), #15.9.6.
FORMULA
It appears a(n) = 2^(n+1)*GAMMA(n+5/2)*(n^2+n)*(10*n^2+15*n+2)/(405*Pi^(1/2)). - Mark van Hoeij, Oct 26 2011.
G.f.: x*(7*(5-30*x) * hypergeom([4, 9/2],[],2*x) - 26*hypergeom([3, 7/2],[],2*x))/9. - Mark van Hoeij, Apr 07 2013
(n-1)*(10*n^2-5*n-3)*a(n) - (2*n+3)*(n+1)*(10*n^2+15*n+2)*a(n-1) = 0. - R. J. Mathar, Jun 09 2018
MAPLE
gf := (u, t)->exp(u*(exp(t)-1-t)); S2a := j->simplify(subs(u=0, t=0, diff(gf(u, t), u$j, t$(2*j+3)))/j!); for i from 1 to 20 do S2a(i); od; # Barbara Haas Margolius (margolius(AT)math.csuohio.edu), Dec 12 2000
MATHEMATICA
a[n_] := n (n+1) (10n^2+15n+2) (2n+3)!! / 810; Array[a, 20] (* Jean-François Alcover, Feb 09 2016, after Mark van Hoeij *)
CROSSREFS
Sequence in context: A140406 A075512 A223958 * A130646 A038649 A004375
KEYWORD
nonn
EXTENSIONS
More terms from Barbara Haas Margolius (margolius(AT)math.csuohio.edu), Dec 12 2000
STATUS
approved