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=0, l=1).
Conjecture: (n+1)*a(n) +2*(-3*n+1)*a(n-1) +5*(-3*n+7)*a(n-2) +40*(n-3)*a(n-3) +20*(-n+4)*a(n-4)=0. - R. J. Mathar, Mar 02 2016
EXAMPLE
a(2)=2*1*7+1=15. a(3)=2*1*15+7^2+1=80.
MAPLE
l:=1: : k := 0 : m :=7: d(0):=1:d(1):=m: for n from 1 to 28 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, 31); seq(d(n), n=0..29);
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Richard Choulet, May 03 2010
STATUS
approved