-1209

Appears in sequences

• tanh(sec(x)*arctan(x))=x-1/3!*x^3+25/5!*x^5-1209/7!*x^7+68945/9!*x^9...at n=3A012809
• Hankel transform of number of divisors sequence (A000005).at n=20A056225
• Triangle T(n,k) read by rows: coefficient [x^k] of the polynomial p(n,x) with p(0,x) = 1, p(1,x) = 2 - x, p(2,x) = 1 - 4*x + x^2 and p(n,x) = (2-x)*p(n-1,x) - p(n-2,x) if n>2.at n=50A136674
• Coefficients of the eighth-order mock theta function T_0(q).at n=53A153155
• Dirichlet g.f.: 1 / (zeta(s) * zeta(s-1) * zeta(s-2)).at n=44A328254
• E.g.f. satisfies: A(x) * log(A(x)) = 1 - exp(-x*A(x)^2).at n=7A349602