OFFSET
4,1
REFERENCES
L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 261.
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
From Barbara Haas Margolius (margolius(AT)math.csuohio.edu), Mar 12 2001: (Start)
E.g.f.: (1/2)*u(x)^3+(11/2)*u(x)-2*u(x)^2-(x/2)*u(x)^2+x/2, where u(x)=sec(x)+tan(x), n>3.
a(n) ~ 2n!(2/Pi)^(n+1)((4n^2+12n+8)/(Pi^2)-8(n+1)/Pi+5-n). (End)
E.g.f.: (5 * cos(x) + 2*x * sin(x) - 3*x - 4) / (1 - sin(x)) + (1 + sin(x)) / ((1 - sin(x)) * cos(x)) - 2. - Michael Somos, Aug 28 2012
EXAMPLE
2*x^4 + 28*x^5 + 236*x^6 + 1852*x^7 + 14622*x^8 + 119964*x^9 + 1034992*x^10 + ... . - Michael Somos, Aug 28 2012
MAPLE
seq(coeff(series(2*tan(t)*sec(t)^2+4*sec(t)+5*tan(t)-4*sec(t)*tan(t)-1-4*sec (t)^2-t*sec(t)*tan(t)+2*sec(t)^3-t*sec(t)^2, t, 30), t, i)*i!, i=4..24); # Barbara Haas Margolius (margolius(AT)math.csuohio.edu), Mar 12 2001
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
More terms from Barbara Haas Margolius (margolius(AT)math.csuohio.edu), Mar 12 2001
Offset corrected by N. J. A. Sloane, Aug 27 2012 at the suggestion of Michael Somos
STATUS
approved