OFFSET
0,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..1000
FORMULA
G.f.: ((2*x-1) *sqrt(-3*x^2-2*x+1)+2*x^3-3*x+1)/ (6*x^6+x^5 +sqrt(-3*x^2-2*x+1) *(3*x^4-x^3)-4*x^4+x^3). - Vladimir Kruchinin, May 24 2014
a(n) ~ 3^(n+2)/2 * (1-3*sqrt(3)/(2*sqrt(Pi*n))). - Vaclav Kotesovec, May 24 2014
MATHEMATICA
Table[Sum[Binomial[n+2, i]*Sum[Binomial[i, j], {j, 0, n-i}], {i, 0, n+2}], {n, 0, 20}] (* Vaclav Kotesovec, May 24 2014 *)
PROG
(PARI) x='x+O('x^50); Vec(((2*x-1)*sqrt(-3*x^2-2*x+1)+2*x^3-3*x+ 1)/(6*x^6 +x^5 + sqrt(-3*x^2-2*x+1)*(3*x^4-x^3)-4*x^4+x^3)) \\ G. C. Greubel, May 23 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, May 07 2000
STATUS
approved