-2403763488domain: ZAppears in sequencesExpansion of (1 + x)^2/((1 + x + x^2)*(1 + 3*x + x^2)).at n=23A113066Expansion of -x/((x^2+x+1)*(x^2+3*x+1)); invert transform gives signed version of tetrahedral numbers A000292.at n=23A113067