458649

Appears in sequences

• a(n) = P_n(9), where P_n is n-th Legendre polynomial; also, a(n) = central coefficient of (1 + 9*x + 20*x^2)^n.at n=5A084769
• a(n) = Sum_{k=0..n} (-1)^(n - k) * binomial(n,k) * binomial(n+k,k) * n^k.at n=5A331657
• Square array T(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of 1/sqrt(1 - 2*(2*k+1)*x + x^2).at n=50A335333
• P_5(2n+1), the Legendre polynomial of order 5 at 2n+1.at n=4A335338