346846domain: NAppears in sequencesSemi-meanders: number of ways a semi-infinite directed curve can cross a straight line n times.at n=14A000682Number of rotationally symmetric closed meanders of length 4n+2.at n=7A060206G.f.: Sum_{n>=0} (n+1)*(n+2)/2 * x^n * (1 + x^n)^n.at n=72A326003