2189187

Appears in sequences

• Expansion of 1/(1-3*x)^9; 9-fold convolution of A000244 (powers of 3).at n=6A036222
• E.g.f.: S(x) satisfies: S(x) = Integral sqrt( (1 + S(x)^2)*(1 + 2*S(x)^2) ) dx.at n=5A289695
• Triangle read by rows: T(n,k) = 3^(n-k)*C(2*n,n-k).at n=29A386825