OFFSET
4,2
COMMENTS
Apparently the Motzkin transform of the 6th row of A025117, i.e., of 1, 4, 11, 20, ..., 11, 4, 1 followed by zeros. - R. J. Mathar, Dec 11 2008
FORMULA
G.f.: z(1-z)M^5, with M the g.f. of the Motzkin numbers (A001006).
Conjecture: -(n+6)*(n-4)*a(n) +(4*n^2-n-51)*a(n-1) +(-2*n^2+11*n+18)*a(n-2) -(4*n-1)*(n-3)*a(n-3) +3*(n-3)*(n-4)*a(n-4)=0. - R. J. Mathar, Jun 23 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved