First differences of A006128.

Terms

a(0) =1a(1) =2a(2) =3a(3) =6a(4) =8a(5) =15a(6) =19a(7) =32a(8) =42a(9) =64a(10) =83a(11) =124a(12) =157a(13) =224a(14) =288a(15) =395a(16) =502a(17) =679a(18) =854a(19) =1132a(20) =1422a(21) =1847a(22) =2307a(23) =2968a(24) =3677a(25) =4671a(26) =5772a(27) =7251a(28) =8908a(29) =11110