We discover that the 26D open bosonic string scattering amplitudes (SSA) of three tachyons and one arbitrary string state can be expressed in terms of the D-type Lauricella functions with associated S L (K+ 3 , ℂ) symmetry. As a result, SSA and symmetries or relations among SSA of different string states at various limits calculated previously can be rederived. These include the linear relations first conjectured by Gross [1-5] and later corrected and proved in [6-12] in the hard scattering limit, the recurrence relations in the Regge scattering limit with associated S L (5 ℂ) symmetry [24-26] and the extended recurrence relations in the nonrelativistic scattering limit with associated S L (4 ℂ) symmetry  discovered recently. Finally, as an application, we calculate a new recurrence relation of SSA which is valid for all energies.
- Bosonic Strings
- Higher Spin Symmetry