  We relate Pandharipande-Thomas stable pair invariants on Calabi-Yau 3-folds
containing the projective plane with those on the derived equivalent orbifolds
via wall-crossing method. The difference is described by generalized
Donaldson-Thomas invariants counting semistable sheaves on the local projective
plane, whose generating series form theta type series for indefinite lattices.
Our result also derives non-trivial constraints among stable pair invariants on
such Calabi-Yau 3-folds caused by Seidel-Thomas twist.
