OFFSET
0,2
FORMULA
G.f f: f(z)=(1-sqrt(1-4*z*(a(0)-z*a(0)^2+z*a(1)+(k+l)*z^2/(1-z)+k*z^2/(1-z)^2)))/(2*z) (k=-1, l=1).
Conjecture: (n+1)*a(n) +(2-7n)*a(n-1) +3(17-7n)*a(n-2) +9(11n-34)*a(n-3) +108(4-n)*a(n-4) +36(n-5)*a(n-5)=0. - R. J. Mathar, Nov 27 2011
EXAMPLE
a(2)=2*1*10-2+1=19. a(3)=2*1*19-2+100-1+1=136.
MAPLE
l:=1: : k := -1 : for m from 0 to 10 do d(0):=1:d(1):=m: for n from 1 to 30 do d(n+1):=sum(d(p)*d(n-p)+k, p=0..n)+l:od :
taylor((1-sqrt(1-4*z*(d(0)-z*d(0)^2+z*m+(k+l)*z^2/(1-z)+k*z^2/(1-z)^2)))/(2*z), z=0, 30); seq(d(n), n=0..30): od;
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Richard Choulet, May 04 2010
STATUS
approved