Sum of exponents in prime-power factorization of C(4n,n).

Terms

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