  Unanticipated connections between different fragments of lambda calculus and
different families of embedded graphs (a.k.a. "maps") motivate the problem of
enumerating $\beta$-normal linear lambda terms. In this brief note, it is shown
(by appeal to a theorem of Arqu\`es and Beraud) that the sequence counting
isomorphism classes of $\beta$-normal linear lambda terms up to free exchange
of adjacent lambda abstractions coincides with the sequence counting
isomorphism classes of rooted maps on oriented surfaces (A000698).
