OFFSET
0,2
COMMENTS
a(n) is also the coefficient of X^n in the polynomial that expresses the x-coordinate after N iterations, for any N greater than n.
EXAMPLE
Pos. 0: ( X+[0], X)
Pos. 1: ( [2]*X , X^2)
Pos. 2: ( [1]*X^2 + 2 *X , 2*X^3)
Pos. 3: ( [2]*X^3 + 1 *X^2 + 2 *X , 2*X^5+4*X^4)
Pos. 4: (2*X^5 + [4]*X^4 + 2 *X^3 + 1 *X^2 + 2 *X , 4*X^8+10*X^7+8*X^6+8*X^5)
PROG
(PARI)
list_a(nmax)= {
my(n=0, v=[Ser(x, x, nmax), Ser(x, x, nmax)], f=v->[v[1]+v[2], v[1]*v[2]]); print1("0, ");
while(n<nmax, n++; v=f(v); print1(polcoeff(v[1], n), ", "))}
list_a(30)
CROSSREFS
KEYWORD
nonn
AUTHOR
Luc Rousseau, May 05 2021
STATUS
approved