1 + sum of first n 3-almost primes.

Terms

a(0) =1a(1) =9a(2) =21a(3) =39a(4) =59a(5) =86a(6) =114a(7) =144a(8) =186a(9) =230a(10) =275a(11) =325a(12) =377a(13) =440a(14) =506a(15) =574a(16) =644a(17) =719a(18) =795a(19) =873a(20) =965a(21) =1063a(22) =1162a(23) =1264a(24) =1369a(25) =1479a(26) =1593a(27) =1709a(28) =1826a(29) =1950