The decays B+→J/ψ3π+2π− and B+→ψ(2S)π+π+π− are observed for the first time using a data sample corresponding to an integrated luminosity of 3.0 fb−1, collected by the LHCb experiment in proton–proton collisions at the centre-of-mass energies of 7 and 8TeV. The branching fractions relative to that of B+→ψ(2S)K+ are measured to be
B(B+→J/ψ3π+2π−)B(B+→ψ(2S)K+)=B(B+→ψ(2S)π+π+π−)B(B+→ψ(2S)K+)=(1.88±0.17±0.09)×10−2,(3.04±0.50±0.26)×10−2,
where the first uncertainties are statistical and the second are systematic.