OFFSET
3,4
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 3..1000
FORMULA
G.f.: (-x/2)*( 2 + (2*x^4-x^2-1)/(sqrt(1-4*x^4)*(1+x^2)) + (2*x^2-x-1)/(sqrt(1-4*x^2)*(1+x)) ) - Herman Jamke (hermanjamke(AT)fastmail.fm), Nov 01 2006
a(2n+4) = A006134(n-1) = Sum[ (2k)!/(k!)^2, {k,0,n} ]. - Alexander Adamchuk, Feb 23 2007
MATHEMATICA
CoefficientList[Series[(- x/2) (2 + (2*x^4 - x^2 - 1) / (Sqrt[1 - 4 x^4] (1 + x^2)) + (2 x^2 - x - 1) / (Sqrt[1 - 4 x^2] (1 + x))) / x^3, {x, 0, 40}], x] (* Vincenzo Librandi, May 17 2013 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Ralf Stephan, Jan 03 2003
EXTENSIONS
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Nov 01 2006
STATUS
approved