1706934domain: NAppears in sequencesINVERTi transform of central trinomial coefficients (A002426).at n=18A007971Expansion of 1 - x - sqrt(1 - 2*x - 3*x^2) in powers of x.at n=18A126068Expansion of 2 - x - sqrt(1-2x-3x^2).at n=18A168055