Sum of exponents in prime-power factorization of C(3n,n).

Terms

a(0) =0a(1) =1a(2) =2a(3) =4a(4) =4a(5) =4a(6) =6a(7) =8a(8) =6a(9) =7a(10) =8a(11) =11a(12) =11a(13) =11a(14) =11a(15) =12a(16) =10a(17) =12a(18) =11a(19) =15a(20) =13a(21) =13a(22) =18a(23) =18a(24) =17a(25) =16a(26) =17a(27) =19a(28) =17a(29) =18