From George Gilbert's marks problem: jumping 4 marks at a time (initial positions).

Terms

a(0) =1a(1) =2a(2) =3a(3) =7a(4) =14a(5) =30a(6) =33a(7) =66a(8) =177a(9) =227a(10) =686a(11) =932a(12) =1283a(13) =1623a(14) =1827a(15) =3603a(16) =7429a(17) =15750a(18) =16438a(19) =18650a(20) =22139a(21) =22967a(22) =31412a(23) =35482a(24) =36075a(25) =62639a(26) =128086a(27) =175642a(28) =201758a(29) =239985