a(3)=5, a(4)=8, a(5)=12; thereafter a(n) = a(n-1) + A000931(n+7).

Terms

a(0) =5a(1) =8a(2) =12a(3) =19a(4) =28a(5) =40a(6) =56a(7) =77a(8) =105a(9) =142a(10) =191a(11) =256a(12) =342a(13) =456a(14) =607a(15) =807a(16) =1072a(17) =1423a(18) =1888a(19) =2504a(20) =3320a(21) =4401a(22) =5833a(23) =7730a(24) =10243a(25) =13572a(26) =17982a(27) =23824a(28) =31563a(29) =41815