a(1) = 1; for n>1, a(n) = a(n-1) + 1 + sum of distinct prime factors of a(n-1) that are < a(n-1).

Terms

a(0) =1a(1) =2a(2) =3a(3) =4a(4) =7a(5) =8a(6) =11a(7) =12a(8) =18a(9) =24a(10) =30a(11) =41a(12) =42a(13) =55a(14) =72a(15) =78a(16) =97a(17) =98a(18) =108a(19) =114a(20) =139a(21) =140a(22) =155a(23) =192a(24) =198a(25) =215a(26) =264a(27) =281a(28) =282a(29) =335