608151037123domain: NAppears in sequencesa(n) = T(2*n,n), T given by A026736.at n=20A026737Sum of squares of numbers in row n of array T given by A026736.at n=20A027221Number of permutations avoiding the patterns {3241,3421,4321}; number of weak sorting class based on 3241.at n=21A111279