542648domain: NAppears in sequencesExpansion of e.g.f. exp((sin(x) + sinh(x))/2).at n=15A306347a(0) = 1; a(n) = Sum_{k=0..floor((n-1)/4)} binomial(n-1,4*k) * a(k) * a(n-4*k-1).at n=15A351969