-18480

Appears in sequences

• Bisection of A002470.at n=31A002286
• sech(tanh(x)*arctan(x))=1-12/4!*x^4+480/6!*x^6-18480/8!*x^8...at n=4A012687
• Triangle of coefficients, read by rows, where T(n,k) is the coefficient of x^n*y^k in f(x,y) that satisfies f(x,y) = (1+x) - x^2*(1+x)^2 + xy*f(x,y)^2.at n=61A086612
• Irregular triangular array a(n,m) for third (k=3) convolution of Chebyshev's S(n,x) = U(n,x/2) polynomials, read by rows (n >=0, 0 <= m <= floor(n/2)).at n=45A128505
• Triangle read by rows, coefficients of the Legendre polynomials P(n, x) times 2^n: T(n, k) = 2^n * [x^k] P(n, x), n >= 0, 0 <= k <= n.at n=48A157077
• E.g.f.: exp(x^2/(1 + x + x^2)).at n=8A293589