177280

Appears in sequences

• E.g.f.: Sum_{n >= 0} a(n) * x^(2*n) / (2*n)! = sin(x)^2 / cos(2*x).at n=4A000816
• E.g.f.: cos(x)^2 / cos(2x) = Sum_{n >= 0} a(n) * x^(2n) / (2n)!.at n=4A000819
• Expansion of (sin^2 x + sin x) /cos 2x.at n=8A000822
• E.g.f. cos(x)/(cos(x) - sin(x)).at n=8A000828
• Triangle of Arnold L(b) for Springer numbers.at n=44A256665
• A signed triangle of V. I. Arnold for the Springer numbers (A001586).at n=36A256679
• A family of sequences converging to the exponential limit of sec + tan (A320956). Square array A(n, k) for n >= 0 and k >= 0, read by descending antidiagonals.at n=57A321400
• a(n) = 2^n*E2_{n}(1/2) with E2_{n} the polynomials defined in A326480.at n=7A326483