-3116domain: ZAppears in sequencesImaginary part of (1+2i)^n.at n=10A006496a(n) = 5^n*sin(2n*arctan(1/2)) or numerator of tan(2n*arctan(1/2)).at n=4A066770Expansion of 1/(1 - 4*x + 5*x^2).at n=9A099456Real part of (4 + 3i)^n.at n=5A139030E.g.f. A(x) = Sum_{n>=1} a(n)*x^n/n! is inverse function to exp(x) - x^2 - 1.at n=6A185151