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A001880
Coefficients of Bessel polynomials y_n (x).
(Formerly M4989 N2146)
13
1, 15, 210, 3150, 51975, 945945, 18918900, 413513100, 9820936125, 252070693875, 6957151150950, 205552193096250, 6474894082531875, 216659917377028125, 7675951358500425000, 287080580807915895000, 11303797869311688365625, 467445288360359818884375
OFFSET
4,2
REFERENCES
J. Riordan, Combinatorial Identities, Wiley, 1968, p. 77.
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).
FORMULA
E.g.f.: x*(1 + x/2)/(1 - 2*x)^(7/2); or, if shifted, (1+ 6x+ 3x^2/2!) / (1-2x)^(9/2).
a(n) = (2*n-4)!/(4!*(n-4)!*2^(n-4)).
(n-4)*a(n) = (n-2)*(2*n-5)*a(n-1) for n = 5, 6, .. , with a(4) = 1. - Johannes W. Meijer, May 24 2009
G.f.: x^4*2F0(5/2,3;;2x). - R. J. Mathar, Aug 08 2015
MATHEMATICA
nn = 25; t = Range[0, nn]! CoefficientList[Series[x (1 + x/2)/(1 - 2 x)^(7/2), {x, 0, nn}], x]; Drop[t, 1] (* T. D. Noe, Aug 10 2012 *)
PROG
(PARI) x='x+O('x^50); Vec(serlaplace(x*(1 + x/2)/(1 - 2*x)^(7/2))) \\ G. C. Greubel, Aug 13 2017
CROSSREFS
See A001518.
Column 4 of triangle A001497.
Equals the second right hand column of the triangles A094665 and A083061.
Other right hand columns are A001147, A160470, A160471 and A160472.
Sequence in context: A170696 A170734 A186231 * A240682 A113362 A252875
KEYWORD
nonn,easy
STATUS
approved