1718640

Appears in sequences

• One half of A075178.at n=29A075179
• Positive numbers differing from next 3 greater squares by squares.at n=32A218487
• a(n) = (4*n)!/((n!)^2*(2*n)!)*Sum_{k=0..n} binomial(n,k)^2*binomial(2*k,k).at n=3A381199
• E.g.f. A(x) satisfies A(x) = exp( x^2*A(x)^2 / (1 - x*A(x))^3 ).at n=7A387949