OFFSET
0,3
COMMENTS
Diagonal of A071946. - Emeric Deutsch, Dec 15 2004
Last (largest) number of each row of A071946. - David Scambler, May 15 2012
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..1000
D. Merlini et al., Underdiagonal lattice paths with unrestricted steps, Discrete Appl. Math., 91 (1999), 197-213 (d_n page 209).
FORMULA
G.f. (offset 1) is series reversion of (x-x^2)/(1+x^3).
MAPLE
A071969 := n->add( binomial(n+1, k)*binomial(2*n-3*k, n-3*k)/(n+1), k=0..floor(n/3));
Order:=30: g:=solve(series((H-H^2)/(1+H^3), H)=z, H): seq(coeff(g, z^n), n=1..28); # Emeric Deutsch, Dec 15 2004
MATHEMATICA
Table[Sum[Binomial[n+1, k] Binomial[2n-3k, n-3k]/(n+1), {k, 0, Floor[n/3]}], {n, 0, 40}] (* Harvey P. Dale, Jul 20 2022 *)
PROG
(PARI) a(n)=if(n<0, 0, polcoeff(serreverse((x-x^2)/(1+x^3)+x^2*O(x^n)), n+1))
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jun 17 2002
STATUS
approved