a(n) = 2 + floor((1 + Sum_{j=1..n-1} a(j))/5).

Terms

a(0) =2a(1) =2a(2) =3a(3) =3a(4) =4a(5) =5a(6) =6a(7) =7a(8) =8a(9) =10a(10) =12a(11) =14a(12) =17a(13) =20a(14) =24a(15) =29a(16) =35a(17) =42a(18) =50a(19) =60a(20) =72a(21) =87a(22) =104a(23) =125a(24) =150a(25) =180a(26) =216a(27) =259a(28) =311a(29) =373