a(n) = 5 + floor( Sum_{j=1..n-1} a(j)/3 ).

Terms

a(0) =5a(1) =6a(2) =8a(3) =11a(4) =15a(5) =20a(6) =26a(7) =35a(8) =47a(9) =62a(10) =83a(11) =111a(12) =148a(13) =197a(14) =263a(15) =350a(16) =467a(17) =623a(18) =830a(19) =1107a(20) =1476a(21) =1968a(22) =2624a(23) =3499a(24) =4665a(25) =6220a(26) =8293a(27) =11058a(28) =14744a(29) =19658