OFFSET
0,4
COMMENTS
FORMULA
G.f. = 1/sqrt((1-tz-z^2)^2-4z^2).
EXAMPLE
Triangle starts:
1;
0, 1;
3, 0, 1;
0, 8, 0, 1;
13, 0, 15, 0, 1;
0, 57, 0, 24, 0, 1;
T(3,1)=8 because we have hH, Hh, hUD, UhD, UDh, hDU, DhU and DUh.
MAPLE
G:=1/sqrt((1-t*z-z^2)^2-4*z^2): Gser:=simplify(series(G, z=0, 15)): for n from 0 to 11 do P[n]:=sort(coeff(Gser, z, n)) end do: for n from 0 to 11 do seq(coeff(P[n], t, j), j=0..n) end do; # yields sequence in triangular form
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Emeric Deutsch, Sep 03 2007
STATUS
approved