Number of times n must be differentiated to reach 0.

Terms

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