a(n) = A000108(n) + A000079(n) - 1.

Terms

a(0) =1a(1) =2a(2) =5a(3) =12a(4) =29a(5) =73a(6) =195a(7) =556a(8) =1685a(9) =5373a(10) =17819a(11) =60833a(12) =212107a(13) =751091a(14) =2690823a(15) =9727612a(16) =35423205a(17) =129775861a(18) =477900843a(19) =1767787477a(20) =6565168995a(21) =24468364171a(22) =91486757943a(23) =343068002257