A373816 Expansion of 1/(2 - 1/(1 - 4*x)^(3/2)).
1, 6, 66, 716, 7746, 83748, 905332, 9786456, 105788610, 1143539764, 12361276668, 133621178280, 1444399211188, 15613460929512, 168776165962152, 1824412555458480, 19721274932411586, 213180228200294100, 2304405260270678316, 24909831687105112968
Offset: 0
Programs
-
PARI
my(N=20, x='x+O('x^N)); Vec(1/(2-1/(1-4*x)^(3/2)))
Formula
a(n) = 4^n * Sum_{k>=0} (1/2)^(k+1) * binomial(n-1+3*k/2,n).