Number of 4's when n is written in base b for 2<=b<=n+1.

Terms

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