OFFSET
0,3
COMMENTS
P_n(x) has degree A002620(n).
LINKS
EXAMPLE
Triangle begins:
1
1
2
2,1
2,1,2
2,1,2,2,1
2,1,2,2,3,1,2
2,1,2,2,3,3,3,2,2,1
2,1,2,2,3,3,5,3,4,3,3,1,2
2,1,2,2,3,3,5,5,5,5,5,4,5,3,2,2,1
MAPLE
P[0]:=1; P[1]:=1; d:=[0, 0]; M:=14; for n from 2 to M do P[n]:=expand(P[n-1]+q^(n-2)*P[n-2]);
lprint(seriestolist(series(P[n], q, M^2))); d:=[op(d), degree(P[n], q)]; od: d;
CROSSREFS
KEYWORD
nonn,tabf
AUTHOR
N. J. A. Sloane, Apr 10 2007
STATUS
approved