11070525440
domain: N
Appears in sequences
- Expansion of e.g.f. (1 + tan(x))/(1 - tan(x)).at n=12A000831
- E.g.f.: Sum_{n >= 0} a(n)*x^(2*n)/(2*n)! = sec(2*x).at n=6A002436
- Expansion of e.g.f. log(1 + tan(x)).at n=13A003707
- Square array A(n,k), n>=0, k>=0, read by antidiagonals, where column k is the expansion of continued fraction 1/(1 - 2^k*x/(1 - 4^k*x/(1 - 6^k*x/(1 - 8^k*x/(1 - 10^k*x/(1 - ...)))))).at n=42A291260
- a(n) = 2^n*E2_{n}(1/2) with E2_{n} the polynomials defined in A326480.at n=12A326483
- Triangle read by rows: T(n, k) = (-1)^(n-k) * (2*n + 1)! * [y^(2*k)] [x^(2*n+1)] arctan(sec(x*y)*tanh(x)).at n=21A371687