-14701568domain: ZAppears in sequencesE.g.f. is the logarithmic derivative of e.g.f. for Pell numbers [1, 0, 1, 2, 5, ...].at n=12A006673Expansion of e.g.f.: 2*cos(r*x)^2 / (1 + cos(r*x)^2) where r = sqrt(2), even terms only.at n=6A263249