Number of trivalent maps with n nodes.

Terms

a(0) =1a(1) =2a(2) =4a(3) =16a(4) =63a(5) =328a(6) =1933a(7) =12633a(8) =87466a(9) =633015a(10) =4717745a(11) =35980100a(12) =279418926a(13) =2202903618a(14) =17590599410a(15) =142025760202