a(n) = a(n - 1) + a(n - 2) + a(n - 3) for n>2, a(0)=5, a(1)=7, a(2)=9.

Terms

a(0) =5a(1) =7a(2) =9a(3) =21a(4) =37a(5) =67a(6) =125a(7) =229a(8) =421a(9) =775a(10) =1425a(11) =2621a(12) =4821a(13) =8867a(14) =16309a(15) =29997a(16) =55173a(17) =101479a(18) =186649a(19) =343301a(20) =631429a(21) =1161379a(22) =2136109a(23) =3928917a(24) =7226405a(25) =13291431a(26) =24446753a(27) =44964589a(28) =82702773a(29) =152114115