Length of longest contiguous block of 1's in binary expansion of n.

Terms

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