15665664domain: NAppears in sequencesa(n) = coefficient of x^n in the (2^(n+1))-th iteration of x+x^2 for n>=1.at n=4A158263Table where row n lists the coefficients in the (2^n)-th iteration of x+x^2 for n>=0, read by antidiagonals not including trailing zeros in rows.at n=46A158264