Length of row n of A143589 (a Kolakoski fan).

Terms

a(0) =1a(1) =1a(2) =2a(3) =2a(4) =3a(5) =4a(6) =7a(7) =10a(8) =16a(9) =24a(10) =36a(11) =54a(12) =80a(13) =120a(14) =180a(15) =269a(16) =404a(17) =605a(18) =908a(19) =1361a(20) =2041a(21) =3063a(22) =4591a(23) =6890a(24) =10333a(25) =15509a(26) =23259a(27) =34901a(28) =52344a(29) =78516